"Bitcoin has failed. The failures weren’t inevitable; there are solutions to these problems in the acdemic literature. But Bitcoin was deployed by enthusiasts who in essence let experimental code escape from a lab to the world, without thinking about the engineering issues—and now they’re stuck with it."

"The belief or hope that there will always be a greater fool wanting to buy is supposed to be underwritten by bitcoin’s “limited edition” status – a limited number can be produced. Which makes bitcoin buyers more like stamp collectors – or perhaps rare coin collectors."

"The only difference between Bitcoin No. ABC123 and $1 Bill No. L88793293J is that at the end of the day, the $1 bill physically exists and has a face value that is worth something. Fred could take the $1 bill and buy something off the $1 menu at McDonalds….By contrast, Bitcoin has no intrinsic value — it is just a number. The number may have an agreed value between two parties, but the number itself has no value."

"So when I ask “What is bitcoin good for?” the answer I come up with is “not enough to justify anything like these valuations.” There are all sorts of interesting applications for cryptocurrencies and blockchains. But unless they become a global currency, or a global payment system, I don’t see why, 50 years from now, anyone is going to be willing to pay tens of thousands of dollars to get their hands on one."

"Morgan Stanley analyst James Faucette and his team sent a research note to clients a few days ago suggesting that the real value of bitcoin might be … $0."

"So the next time the wizards of speculation produce yet another financial collapse, who ya gonna call? Bitcoin? Sorry, there’s nobody home."

"Everyone says the blockchain, the technology underpinning cryptocurrencies such as bitcoin, is going to change EVERYTHING. And yet, after years of tireless effort and billions of dollars invested, nobody has actually come up with a use for the blockchain—besides currency speculation and illegal transactions."

"These currencies are going to trade to zero or pretty close to it when the bubble pops. Right now, the only reason why people are buying bitcoin is because the price is going up. When it turns around, they are not going to sell it for the same reason. There is no value in bitcoin, you can’t use it as money. It’s too slow, too expensive and too vulnerable."

"The old bitcoin network is virtually useless. Many bitcoin investors haven’t understood these risks because they have only been buying the cryptocurrency – but never sold or traded them. As soon as people realize that this is how it works, they will start to sell."

"It’s got this mystique about it, because it’s some fancy technological thing that nobody really understands. There’s been no demonstration yet that it actually is helpful in conducting economic transactions. There’s no anchor for its value. You know, unlike pieces of paper with dead presidents on them, those are anchored by the fact that you can use them to pay taxes. There’s not anchor for bitcoin. But bitcoin has developed this mystique."

"Bitcoin is the World’s first distributed, decentralised Ponzi scheme. No single operator is running it, and everyone has a chance to participate in it, but its value is determined purely by the weight of money coming into it and the willingness of holders to sell it. Like any Ponzi scheme, earlier participants came in at lower cost, and are now receiving much of the billions of dollars (yes, really) that newcomers are putting in."

"Few people use bitcoin to buy anything — but everyone pays for its environmental impact."

"Bitcoin has become a Ponzi scheme for redistributing wealth from one libertarian to another. Actually, I would like to amend that a little bit: Bitcoin has now graduated to being a Ponzi scheme for redistributing wealth from one person to another."

"Bitcoin and the like will quickly fade into financial history, just as tulipmania did, serving solely to remind future generations of the folly of gambling on illusions of value."

"Ultimately, I think bitcoin has really no value. In the market, it has plenty of value. As long as there’s buying, there’s value. But when the buying goes away, so does the value."

"Bitcoin is more like a limited edition toy than an investment. It has no value except for the sheer hope that it will one day become valuable."

"The CME futures may institutionalize bitcoin, which would be disastrous [for the environment]."

"Former Federal Reserve Chairman Alan Greenspan told CNBC on Wednesday that bitcoin reminds him of currency issued during America’s Colonial past that ultimately proved worthless. “Humans buy all sorts of things that aren’t worth anything,” Greenspan said. “People gamble in casinos when the odds are against them. It has never stopped anybody.”"

"On Monday, the chairman of France’s market regulator denounced Bitcoin as a “dangerous illusion” and a tool for criminals. “It’s a way to purchase illicit goods, it’s a way to launder illicit income, it’s a way to develop and pay for cybercrimes and it’s a pure empty commodity,” Robert Ophele, chairman of the Autorite des Marches Financiers, said in a Bloomberg Television interview from Tokyo. “If it were a currency, it would be a very bad one.”"

"With the price of bitcoin moving toward $12,000, a top economist on Tuesday sent a stark warning to investors: The cryptocurrency is in a “dangerous speculative bubble.” Roach suggested that exchange legitimization makes bitcoin “somewhat dangerous” for investors, given what he described as a “lack of intrinsic underlying economic value to the concept.”"

"Personally I’m very skeptical of bitcoin, I know where the price action is. It’s, you know, going up about 10% a day at this point. Although bitcoin could go up to 20,000, it can go to 30,000. It’s on it’s way to zero — somewhere between zero and 200. It’s a utility token for criminals, terrorists, money launderers, tax evaders — they’ll always find some use for it. So it might not go all the way to zero. It’s clearly a bubble — it looks like the second biggest bubble in history after tulip mania. Although at the rate it’s going it will pass tulip mania, you know, in a matter of days. [It’s] bigger than the south sea bubble, bigger than the Mississippi bubble, New York’s — the Dow Jones in 1929, the Nikkei in 1989 — name your bubble, it’s bigger than all of them."

"For those who may not recall, bitcoin upgraded its blockchain four months ago, boosting its capacity while lowering transaction fees and settlement times. This was done to attract big businesses, but there’s nothing to guarantee that bitcoin’s blockchain will be the preferred choice when there are so many other choices."

"The problem that cryptocurrencies face is that they fail the two key metrics of what makes a currency a currency,” Donovan said. “A currency has to be a widely used medium of exchange. Cryptocurrencies are never going to achieve that. Period.” “The fatal issue for cryptocurrencies is that the supply of them can only ever go up,” he said. “There is unlimited upside to the supply of cryptocurrencies.”"

"It has not transformed the economy of today. While the number of bitcoin transactions is growing every year, it’s nothing close to a mass-market consumer technology, like Google, or Netflix, or even PayPal. Bitcoin remains cumbersome to use (the typical transaction can take up to 10 minutes) and the price is extremely volatile. It is, for now, a frankly terrible currency built on top of a potential transformative technology."

"“So it seems to me it ought to be outlawed,” Stiglitz said Wednesday in a Bloomberg Television interview with Francine Lacqua and Tom Keene. “It doesn’t serve any socially useful function.”"

"Bitcoin is a fake and made-up scam. Can you articulate what it is? “Bullshit jargon that means nothing”-you. Hell no. All we can say for sure about this imaginary “coin” is that it is going to cost you a bundle (sucker)….. Then there are the idiots—like you—who say, “Where I can but some ‘Bitcoin’ to get rich, like all my ‘gamer’ friends?” A wise man once said “What goes up must come down” and another, wiser man once said “All This Bitcoin Stuff Is Fake.” It’s not real, folks."

"Central bankers say the success of bitcoin and other cryptocurrencies is just a bubble….The problem with bitcoin is that it could easily blow up and central banks could then be accused of not doing anything,” ….although technology is revolutionising banking, digital currencies will not replace physical money anytime soon. “It’s too far off.”"

"Even if they were widely accepted by legal merchants, it would at the moment be lunatic to exchange them for anything but real money. Bitcoin itself is trading at more than $8,000, more than 10 times its price a year ago, and more than double what it was three months ago. Since it is only widely used as a currency in drug deals or for ransom payments, there is either a huge boom in criminal activities outside the world of cryptocurrencies, or one within unregulated exchanges where these tokens are traded."

"Bitcoin is dead. It was split in two. There is bitcoin cash, and bitcoin core/legacy. Deal with it."

"We can predict the collapse of the value of Bitcoin, even when it may rise for a little while longer. The introduction of exchange-traded futures may signal the start of this process. Give it a year, maybe less. Bitcoin will become a case study for economics students, teaching them about irrational crowd behaviour."

"We see bitcoin as a bit of a Ponzi scheme,” David Gledhill, group chief information officer and head of group technology and operations at DBS, told CNBC on Wednesday."

"Blockchain technology is here to stay. Blockchain has plenty of uses outside cryptos (smart contracts embedded in Ethereum are one such example), but Bitcoin probably won’t be the reigning technology in the future. It’s overvalued with a limited chance of success, most likely be replaced by a better cryptocurrency."

"I can’t see a future of this when I see the attention played by all governments and regulators on anti-money laundering, on anti-tax evasion, on anti-terrorism financing. The anonymity of the transaction is a problem I think which would put pressure on bitcoin."

"It can hardly be viewed as a store of value. That requires at least a modicum of stability. Unlike the pound in my pocket, however, I can have no idea what a bitcoin will be worth tomorrow or in a year’s time. That, in turn, reduces its value as a unit of account. Why would another individual be prepared to accept my bitcoin for a good or service when its future value is so uncertain; for the same reason, why would I want to spend my volatile bitcoin rather than hoard it in the hope of further appreciation."

"From what we can identify, the only reason today to buy or sell bitcoin is to make money, which is the very definition of speculation and the very definition of a bubble,” he said at a news conference in Zurich on Thursday. He added that in the history of finance, such speculation has “rarely led to a happy end.”"

"People are buying Bitcoin because they expect other people to buy it from them at a higher price; the definition of the greater fool theory. …When the crash comes, and it cannot be too far away, it will be dramatic."

"People get excited from big price movements, and Wall Street accommodates…you can’t value Bitcoin because it’s not a value-producing asset.” It’s a “real bubble."

"One thing is certain: the current scenario is not sustainable."

"Digital currencies, in their current form, should be prohibited by law. And not because they are a Ponzi scheme (which they are), and not because they can help facilitate criminal activity (which they do), but because they incur colossal social waste…."

"I just don’t believe in this bitcoin thing. I think it’s just going to implode one day. I think this is Enron in the making."

"Bitcoin is a fad, just like bimetallism before it."

"I believe it’s not going to succeed in delivering the monetary utility that people expect. I do not think it’s going to be the money of the future. I think it’s the bubble of the present."

"I could care less about bitcoin….I don’t personally understand the value of something that has no actual value. You all can do whatever you want and I don’t care…..If you’re stupid enough to buy it, you’ll pay the price for it one day. I’ve also told people that it can trade at $100,000 before it trades to zero. The only value of bitcoin is what the other guy’ll pay for it. Who cares about bitcoin? The world economy’s so big, JPMorgan alone, $6 trillion, we move all this money, and bitcoin in total, all these currencies, $50 billion dollars, maybe a billion dollars trades a day."

"It’s a black box and I’m not a believer in black boxes. I’m just very suspicious of things that are not transparent. If I can’t understand it, I don’t want to invest in it."

"My best guess is that in the long run, the technology will thrive, but that the price of bitcoin will collapse….it is folly to think that bitcoin will ever be allowed to supplant central-bank-issued money."

"Bitcoin just shows you how much demand for money laundering there is in the world."

"Cryptocurrencies are going up because they are going up; they are the Kardashians of the financial world; famous for being famous. But fame does not last forever, nor do market manias. Then the very same very wise, high profile and analytical financial observers will then try to convince us that they were the first to warn us!"

"The Wolf of Wall Street" Jordan Belfort thinks bitcoin is a fraud,….He expects a central bank to introduce a cryptocurrency of its own “and that’s what will take hold.”"

"Bitcoin has absolutely no value now, and it’s going to cost people a lot of money. Okay, it’s gone from 4,700 to 3,500 in a week, and it’s going to go from 3,500 to zero. Now, it might go from 3,500 to 10,000 first, but it’s going to end up being zero. Bitcoin is a pseudocurrency. It’s no more suitable as money than salt or big round rocks."

"Bitcoin is a sort of tulip. It’s indeed an instrument of speculation for those that want to bet on something that can go up and down 50% or 40% in a few days but certainly not a currency, and certainly we don’t see it as a threat to central banking or monetary policy, that’s for sure."

"Tocqueville’s Chairman John Hathaway doesn’t mince words when it comes to to talking bitcoin. When asked about the cryptocurrency craze, Hathaway, manager of the $1.2 billion dollar Tocqueville gold fund, simply said, ‘garbage.’ “It's an absolute bubble -there's no question in my mind that it's in a bubble."

"Bitcoin is a bubble."

"So is a single bitcoin worth $500,000, $5,000, $500 or $0? I’m inclined to say $0, especially if bitcoin’s value depends on it being adopted as a global digital currency to replace dollars. There is no chance whatsoever that bitcoin can displace the dollar, for the simple reason that it is badly designed. Bitcoin can handle a pathetically small number of transactions, and uses an inordinate amount of electricity to do so, making it entirely unsuitable to replace ordinary money."

"Will that totalitarian regime allow all their central banks and government currencies to be made obsolete by a libertarian cryptocurrency they don’t completely control? Of course not. And anyone who believes Bitcoin will overthrow the globalist money / debt cartels is naive and stupid. Trust me when I say a bunch of geeks aren’t going to overthrow centuries of globalist money domination that now rules our corrupt world."

"JPMorgan’s top quant strategist backed his boss this week in bashing bitcoin, warning that the cryptocurrency is likely a “pyramid scheme.”"

"Computer, biotech, internet shares and real estate, and all crashed when excessive optimism far outweighed the more rational expectations normally associated with prudent investing. So too will be the case with bitcoin."

"It’s just not a real thing, eventually it will be closed. It’s worse than tulip bulbs. It won’t end well."

"UBS and other banks, even some central banks, have adopted blockchain technology that speeds up transactions between the major banks of the world. But you need to separate the underlying technology, which is rather dull, from bitcoin itself, which might be exciting, but it’s not an actual currency."

"Bitcoin’s buzz is gone, for now. It was crushed by the heavy-handed intervention of the Chinese government, which is cooling off investor enthusiasm for the digital currency…."

"The sudden Chinese crackdown on the virtual coin fundraising of bitcoin and other cryptocurrencies that caused the plunge is either the end of the beginning for the crypto-party — or, more likely, the beginning of the end…."

"So here’s my short answer. No, I don’t feel silly, but vindicated. If the recent run-up in bitcoin price proves anything, it’s that the virtual currency is still a dumb investment."

"While we wait for Big Financial to take over this movement, if you own some Bitcoins, sell them now, please. Who cares if you miss some of the run up until it crashes?"

"So, for what it is worth, be warned. If you have investments in crypto currencies, you are invested in a Ponzi scheme. At the end of this, for every winner, there will have to be the same amount of losers. The only way to not end up on the losing side is, to sell before everyone else does."

"Bitcoin is a gigantic bubble ready to explode, according to Euro Pacific Capital CEO Peter Schiff."

"Now enter crypto currencies. Not only will they never become money – a general medium of exchange – as gold and silver once were and will become once again, but cryptos lack the necessary requirements to be money."

"Despite being valued at more than $4,500, #Bitcoin is still just a speculative asset."

"There’s certainly a lot of bullishness about bitcoin and cryptocurrency, and that’s the case with bubbles in general. The psychology of bubbles fuels it. You just become more convinced that it’s going to work. And the higher the price goes, the more convinced you become that you’re right. But it’s not going up because it’s going to work. It’s going up because of speculation…."

"This is why almost none of us should own Bitcoins. Bitcoin value has multiple weaknesses. Someone could hack the blockchain, create more Bitcoins and manipulate the value or sell the illegitimate Bitcoins and abscond with the buyers’ dollars. Or groups of users can place large buys and sells of Bitcoins, manipulating their value, because there are no controls. Or Bitcoin users could simply start using other crypto-currencies or traditional government-issued currencies and the market could fold completely, making Bitcoins worthless, as has happened to other crypto-currencies. Any one, or all, of these things could happen at any moment."

"How can you buy a house, how can buy a car, how can you buy Starbucks with bitcoin when price is going to fluctuate as dramatically as it has. This looks to me like… very much.. you can take the chart of bitcoin and apply it against the tulip bulb mania of the 15th century and the patterns look exactly the same."

"Friends don’t let friends hold bitcoin below $2,900, the line in the sand of sell-stop protection. Otherwise, in the near future, one could be wishing they’d sold this $3,500 zone, as bitcoin breaks under $35, with growing potential for $3.50."

"All these imaginary “digital currencies” are just made up fake things…. Laugh your haughty laugh all you want. Enjoy calling me ignorant. I have a burrito and all you have is “code.” Yeah—code for “idiot.”"

"For now, the development of this bubble is in the hands of a speculating public, who periodically see manias as a failsafe way to make money. But the answer to the question posed in this article’s headline is that cryptocurrencies are not money and never will be."

"Perhaps contrary to the traditional view, therefore, it is unlikely that, as currently conceived, cryptocurrencies will attain the status that the hype would have you believe. They will certainly be revolutionary, but most likely in a manner that will trigger their own demise, or at least relegate their use to those who want to operate outside the legal financial system."

"Howard Marks, billionaire investor and founder of Oaktree Capital Management is adamant about his stance on cryptocurrencies like bitcoin, Ether and others: “They’re not real.”"

"Digital currencies are nothing but an unfounded fad (or perhaps even a pyramid scheme), based on a willingness to ascribe value to something that has little or none beyond what people will pay for it...nobody has been able to make sense to me of these currencies."

"“People are comparing bitcoin to tulip bulbs. I think those comparisons are apt,” he said. “But at least with tulips, you had something tangible — a plant.”"

"A research note out Wednesday by a group of analysts at Morgan Stanley led by James E Faucette said “bitcoin acceptance is virtually zero and shrinking,” despite its impressive appreciation."

"I’ve seen enough cryptocurrency stories over the last few weeks to last me a lifetime, especially about Bitcoin. Bitcoin is not a store of value, and it’s not a reasonable investment candidate. You’ve been warned!"

"We now have enough information on cryptocurrencies to conclude that Bitcoin = Betamax, and Ethereum = VHS. One wins, but both soon obsolete."

"Cryptocurrencies, or cyber currencies, which have been in a massive financial mania until their sudden sell-off this week, have two actual uses: online gambling and money laundering. Neither is the heart of a major business model. But that’s it…. Online currencies are hardly a “store of value” when they have fallen about 30% in a week."

"This revolutionary digital infrastructure will soon be able to process billions more transactions than Bitcoin ever has. It may well be a Bitcoin killer or at best, provide the framework for how blockchain technology could be applied in the real world."

"I think it’s in a bubble. I just don’t know when or how much it corrects. When everyone is bragging about how easy they are making $=bubble"

"Cryptocurrencies do not belong in any investment portfolio. I say this as a Chartered Financial Analyst with 20 years experience who understands the underlying math and the economic issues involved. Fundamentally, Bitcoin has no value… Bitcoin acceptance by consumers is unlikely."

"Play it, own it, do what you like with it, but always remember that it is nothing more that an intrinsically worthless global pyramid scheme that could collapse at any moment."

"Some people will buy it as an “investment.” In my opinion, Monopoly money is safer."

"Similar to the disruptive technologies I listed above, Bitcoin will undergo the standard lifecycle of development… and I believe that will include swift, sweeping government regulation. Similar to gun control, car insurance, cyber regulation and more… However, unlike most of those other technologies, I don’t think Bitcoin will survive this deathblow of regulation."

"Bitcoin itself, it’s doomed. The end is near. Soon as Congress has a reason, they figure out how to shut it down. You mark my words. Too many banks have too much to lose. And if we know one thing, it’s that big banks and Congress are part of the same beast…."

"I used to be an avid trader years ago, and my co-founder is as hardcore of a crypto-anarchist as they come. I would love nothing more than for bitcoin to succeed, but I believe it will die a slow and painful death and something else will come along to be its successor."

"Bitcoin, with all the noise and talk of large scale acquisitions, is just a playground for those wanting a quick buck and will never be part of the genuine electronic financial markets economy."

"The problem with a finite asset is that the economy is not finite, and if you have a limited amount of money to match this almost unlimited capacity of people in the economy to do things, money doesn’t work."

"So if you are “holding” any Bitcoins (not that anyone can actually hold something so ethereal), your moment to exit and flee is rapidly approaching."

"But don’t let that big number fool you: this strange and controversial technology is no closer to becoming a mainstream currency. …Bitcoin is not something the average person will ever use to buy and sell stuff, they say, particularly in the US and other Western countries. The world just doesn’t need a dedicated digital currency."

"As a phenomenon bitcoin has all the attributes of a pyramid scheme, requiring a constant influx of converts to push up the price, based on the promise of its use by future converts. So the ultimate value for bitcoin will be the same as all pyramid schemes: zero."