Should you buy into bitcoin? Here's what top investors say

Bitcoin crossed the $16,000 mark Thursday morning, less than two days after topping $12,000 for the first time. The digital currency now has a market value of more than $272 billion.

Some of the biggest names on Wall Street are embracing the digital currency, including Fundstrat's Tom Lee and value investor Bill Miller, who is running a fund with nearly a third of its assets in bitcoin.

One Dutch family even bet all they have on bitcoin.

Should you be buying into bitcoin too? Here's what top investors have to say:

The cryptocurrency "is a fraud," JPMorgan Chase CEO Jamie Dimon said at the Delivering Alpha conference presented by CNBC and Institutional Investor. "It's just not a real thing, eventually it will be closed."

He added, at a separate conference organized by Barclay, "It's worse than tulip bulbs. It won't end well."

"I think this [crypto] is going to be the biggest bubble of our lifetimes by a long shot," the former Fortress hedge fund manager said at a CoinDesk bitcoin conference.

"To be fair, this is a bubble and there's a lot of fraud mixed in. We look at tons of projects. And some get funded, and they literally look like Ponzi's. There's a lot of froth and fraud in something that's exciting as this."

Novogratz's remarks came right after he gave an aggressive projection for bitcoin: It "could be at $40,000 at the end of 2018. It easily could," he said on CNBC's "Fast Money." And he saw big things for other cryptocurrencies too: "Ethereum, which I think just touched $500 or is getting close, could be triple where it is as well."

According to billionaire Mark Cuban, it's OK to invest up to 10 percent of your savings in high-risk investments, including bitcoin and ethereum. You've just "got to pretend you've already lost your money," he told Vanity Fair, adding that it's like throwing "the Hail Mary."

Bitcoin is a pure gamble, said CNBC's Jim Cramer on "Squawk Box": "It's kind of like Monopoly money. Obviously, there's people who use it. If you ever say anything bad about it, there's like this bitcoin mafia that comes after you. But it is an oddity that has nothing to do with us" as investors.

"It's just pure gambling at this point," the market expert continued. "I mean, if you want to gamble, go to Vegas. Vegas is fabulous."

"In my view, 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," the respected value investor and co-chairman of Oaktree Capital wrote in an investor letter.

The self-made millionaire and best-selling author of "Money: Master the Game" isn't completely sold on the idea yet either.

"I think [bitcoin] is very iffy," Robbins told CNBC's "Fast Money. "I don't have a clue. I look at that as it's like going to Vegas." In other words, only bet what you can afford to lose.

Robbins himself directs a certain amount of money to risky ventures and doesn't rely on them to work out. For those investments, his mentality is, "I know it is just for fun I'm investing, I know I could lose, this is Vegas."

Legendary investor and index fund revolutionary Jack Bogle isn't impressed. He weighed in on the subject at a Council on Foreign Relations event.

"Avoid bitcoin like the plague. Did I make myself clear?" said the Vanguard founder in response to an audience question.

"Bitcoin has no underlying rate of return," Bogle continued. "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."

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