Brian Kelly, an outspoken bitcoin uberbull, told CNBC on Monday that he has nearly all of his money invested in cryptocurrencies.

"Like 90 percent," Kelly estimated on "Squawk Box." "I run a fund. I have my money in that. I've got investments elsewhere."

"But that's not for everybody," said the founder of BK Capital Management, who runs the BKCM Digital Asset Fund. "I'm making a big bet."

That's a big bet indeed, considering bitcoin and other cryptocurrencies make the recent spikes and plunges in the stock market look like child's play.

Bitcoin, the world's largest cryptocurrency, hit a record high of more than $19,000 in mid-December after soaring about 1,300 percent for all of 2017.

But in the new year, bitcoin has been under pressure due to regulatory concerns, hitting a near-term low of under $6,000 last Tuesday. Since then, bitcoin has rebounded more than 40 percent.

Asked whether he can tolerate letting his money ride in a market known for 10 to 20 percent gyrations any given week, Kelly said, "I am comfortable with that."

Kelly said the bull case behind bitcoin and other cryptocurrencies is broader than thinking of them as a payment system — one that is not accepted much in the real world and historically linked with illicit purchases online.

"This is broader than just a currency. I'm making a bet that this is a new asset class in general," he said. Some cryptocurrencies are "privacy-centric" and used on the "dark web," he admitted. But he argued, "You're not talking about as much as you used to."

Kelly said he does see a viable "global digital currency" emerging one day out of the thousands of offerings. "I'm not convinced it will be bitcoin. It could be something else. History of tech tells us tech disrupts itself."