Peter Thiel says he feels underinvested in bitcoin and his only hesitation now is that the secret is out

• Peter Thiel said he feels "underinvested" in bitcoin, Bloomberg reported.
• The tech billionaire said as bitcoin rallies, it's a "complete bankruptcy moment for central banks."

Tech billionaire Peter Thiel said he didn't bet enough on bitcoin, and now he's worried the secret is out.

"I feel like I've been underinvested in it," Thiel told conference attendees in Miami, according to a Bloomberg report. He said he thought everyone already knew the so-called secret about the cryptocurrency. But, "maybe it still is enough of a secret," he said.

"I think the answers are still to go long" on bitcoin, he said, according to Bloomberg.

As the cryptocurrency trades above $65,000, making new all-time-high records, Thiel said it's a "complete bankruptcy moment for the central banks."

Thiel, the outspoken libertarian and founder of PayPal, made the comments at Miami's Perez Art Museum during a conference hosted by the Lincoln Network, a technologist and capitalist non-profit that seeks to bridge "Silicon Valley know-how with D.C. policy," according to its website.

Thiel pointed to the disruptive power of bitcoin at another event earlier in the week. At a Monday night gathering of the conservative Federalist Society, he said bitcoin's rally is a sign the "decrepit regime" is about to blow up. But, he added, now may not be the time to go all-in on the cryptocurrency.

Bitcoin lost its grip on $65,000 early Thursday after reaching a peak just below $67,000 the day before on investor hype around an exchange-traded fund linked to the cryptocurrency.

Another bitcoin futures ETF from asset management firm VanEck is set to start trading next week, following the ProShares fund that hit the market Tuesday.