Cryptocurrencies have become the hottest of hot topics — it seems not a day goes by without some Wall Street VIP or financial luminary proclaiming their stance.

Is bitcoin BTCUSD, -1.58% a “fraud” or the future? Are ICOs just a scam? Depends whom you ask. One thing’s for sure, there’s no shortage of opinions.

Here’s what some of the financial-world heavyweights have had to say lately.

J.P. Morgan Chase & Co. JPM, -0.21% CEO Jamie Dimon:

“ ‘I’m not interested that much in the subject at all.’ ”

Dimon has drawn a lot of flak for calling bitcoin a “fraud” back in September.

He now says he regrets using that word, and that blockchain, or distributed-ledger technology behind cryptocurrencies, is “real.”

The issue, he said, is “what the governments are gonna feel about bitcoin as it gets really big, and I just have a different opinion than other people,” he told Fox Business on Tuesday.

Dimon has compared the rapid ascent of bitcoin with the 17th-century mania over tulip bulbs — viewed as a classic, textbook bubble — and predicted that things may end just as badly for investors in the decentralized currency, which has been surging over the past year.

“Bitcoin will eventually blow up. It’s a fraud. It’s worse than tulip bulbs and won’t end well,” he said in September of last year.

Dimon also said at the time he would fire any trader trading bitcoin for being “stupid.”

His comments caused such a ruckus that Dimon was prompted to proclaim during the bank’s third-quarter earnings call with media that he isn’t going to talk about bitcoin anymore.

“I wouldn’t put this high on the category of important things in the world,” he said.

Warren Buffett, CEO of Berkshire Hathaway BRK.A, +0.36% :

“ ‘They will come to a bad ending.’ ”

Way back in 2014 (a century ago in cryptocurrency time), the Oracle of Omaha said this about bitcoin on CNBC:

“Stay away from it. It’s a mirage, basically. It’s a method of transmitting money. It’s a very effective way of transmitting money and you can do it anonymously and all that. A check is a way of transmitting money too. Are checks worth a whole lot of money? Just because they can transmit money?”

A lot has changed since 2014, but Buffett has doubled-down on his skepticism. He told CNBC on Wednesday: “In terms of cryptocurrencies, generally, I can say with almost certainty that they will come to a bad ending.” He said he wouldn’t short bitcoin and had no interest in trading futures US:XBTF8 US:BTCF8 -- but if five-year put options existed, Buffett said he’d buy one on practically every cryptocurrency that exists.

At an October 2017 event with business school students, Buffett said: “You can’t value bitcoin because it’s not a value-producing asset,” he said. He added that there’s no telling how far bitcoin’s price will go and described it as a “real bubble in that sort of thing.”

Goldman Sachs GS, +0.01% CEO Lloyd Blankfein:

“ ‘Not willing to pooh-pooh it’ ”

“When do I have to have a bitcoin strategy? Not today.” That’s the Goldman boss’s latest take. He continued:

“Bitcoin is not for me. A lot of things that have not been for me in the past 20 years have worked out… but I am not guessing that this will work out.”

The statements fall in line with all the other hedging on crypto he’s done this year. In a CNBC interview in November, Blankfein said that “maybe bitcoin is a kind of a bubble.” But he also said there were “a lot of things that work really, really well today that I thought were stupid and wrong.”

“I don't like [bitcoin], I’m not comfortable with it, I don’t trust it,” he said. “On the other hand, if it works... maybe that was a natural progression from hard money to fiat money to consensus money.”

He also told Bloomberg TV, “I don’t have an investment in it, but I’m not willing to pooh-pooh it.”

In a tweet on Oct. 3, Blankfein cautioned skeptics to consider that the rise of paper money over gold might also have fostered similar doubts from market stalwarts.

Meanwhile, Goldman is reportedly exploring a new trading platform that would be centered on trading in bitcoin and its rivals, like ether.

Jack Bogle, founder of Vanguard Group Inc.:

“ ‘Avoid bitcoin like the plague. Did I make myself clear?’ ”

That was the legendary investor’s response to an audience question at a Council on Foreign Relations event on Nov. 28.

“Bitcoin has no underlying rate of return,” Bogle reportedly said. “You know bonds have an interest coupon, stocks have earnings and dividends, gold has nothing. There is nothing to support bitcoin except the hope that you will sell it to someone for more than you paid for it... Bitcoin may well go to $20,000 but that won’t prove I’m wrong. When it gets back to $100, we’ll talk.”

Credit Suisse Group AG CS, -2.73% CEO Tidjane Thiam:

“ ‘The very definition of a bubble’ ”

Thiam didn’t mince words when addressing cryptocurrencies at a news conference in Zurich on Nov. 2.

“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.

Citigroup C, -1.47% Michael Corbat:

“ ‘Very interested in the technology, not interested in the instrument.’ ”

In an interview with The Nikkei published Oct. 12, Corbat acknowledged the value of blockchain technology, but said he was not interested in the cryptocurrency itself.

“I’m never dismissive of new things. But like many new things, its original application may not or likely won’t be the end state. When we look at bitcoin, we all think and believe that the underlying blockchain technology [is] very valuable. When I look at bitcoin itself, I struggle a bit. What is it? Is it a currency? I don’t necessarily think it is. Is it a speculative investment? Probably more so.”

Morgan Stanley MS, -0.33% CEO James Gorman:

“ ‘More than just a fad’ ”

Gorman came out on the record in late September to argue that the cryptocurrency phenomenon at least is “more than just a fad.”

“I haven’t invested in it. I’ve talked to a lot of people who have. It’s obviously highly speculative but it’s not something that’s inherently bad. It’s a natural consequence of the whole blockchain technology.”

Gorman has said some of the potential attractions of a digital currency are “the privacy protections it gives people,” adding that it is “interesting because what it says to the central banking system about controlling that.”

UBS UBS, -1.95% Chairman Axel Weber:

“ ‘Only a transaction currency’ ”

“I get often asked why I‘m so skeptical about bitcoin, it probably comes from my background as a central banker,” Weber said at a conference in Zurich on Oct. 4.

“The important function of a currency is, it’s a means of payment, it has to be generally accepted, it has to be a store of value and it’s a transaction currency. Bitcoin is only a transaction currency.”

BlackRock CEO Larry Fink:

“ ‘I am a big believer in the potential...’ ”

The rapid ascent of cryptocurrencies “identifies how much money laundering there is being done in the world,” Fink said during a Bloomberg interview with the Wall Street luminary at the BlackRock Fixed Income ETF conference in New York on Oct. 3.

However, he also said: “I am a big believer in the potential in what cryptocurrencies can do.” He said he saw “huge opportunities,” but that presently the atmosphere around bitcoin was “more speculative.”

Ray Dalio, founder of Bridgewater Associates, the world’s largest hedge fund:

“ ‘Bitcoin is a bubble.’ ”

Dalio said in September that cryptocurrencies like bitcoin meet his firm’s criteria for a market bubble, in part because they don’t serve as a reliable storehold of value due to their extreme volatility and signs that people buy them with the sole of intent of selling them later on at a higher price.

“Bitcoin is a highly speculative market,” he told CNBC. “Bitcoin is a bubble.”

Fidelity Investments CEO Abigail Johnson:

“ ‘We need to address the barriers...’ ”

Johnson has come out as a proponent of cryptocurrencies, and has made cryptocurrency balances visible on the investment manager’s website for customers who hold an account with Coinbase — a popular crypto exchange.

“I like to think that huge new markets and products will be built on these platforms,” Johnson said at Consensus, a blockchain-centric conference put on by digital currency site CoinDesk. “But before that can happen, we need to address the barriers there are to adoption — and there are several.”

We laid out the four primary roadblocks she identified here.