"I would be long bitcoin, and neutral to skeptical of just about everything else at this point with a few possible exceptions," Thiel said during a conversation Thursday at the Economic Club of New York. "There will be one online equivalent to gold, and the one you'd bet on would be the biggest."
The PayPal co-founder backed the idea of bitcoin becoming a store of value instead of a go-to currency for daily transactions.
"I'm not talking about a new payments system," Thiel said, adding that bitcoin is too cumbersome for that use case. "It's like bars of gold in a vault that never move, and it's a sort of hedge of sorts against the whole world going falling apart."
Thiel scored a 50 to 80 percent chance that bitcoin ends up being worthless, and said there's a 20 to 50 percent chance it ends up moving higher.
"Probability weighted it's good, and the question of how to time this I'm not going to try to do that precisely," Thiel said.
There's a chance other digital currencies like ethereum could beat bitcoin, and that others down the road may have better features, according to Thiel. But bitcoin's appeal is in its size, he said.
Bitcoin dominated more than 42 percent of total market capitalization among cryptocurrencies Thursday, while ethereum accounted for about 19 percent, according to Coinmarketcap.
"Gold continues to be gold because it's the main asset class," Thiel said. "Maybe it could be replaced by silver but it doesn't seem to be happening."
Founders Fund, run by Thiel, bought about $15 million to $20 million of dollars in bitcoin, the Wall Street Journal reported in early January, citing sources familiar with the situation. Bitcoin rose 9 percent in the 24 hours after the report, according to data from CoinDesk. The digital currency has shed more than 40 percent of its value since then, and was trading near $8,245 as of 4:10 p.m. ET Thursday.
Thiel's optimism did not extend to all digital assets.
"I'm not sure I would encourage people to run out right now and buy these cryptocurrencies," Thiel said.
The venture capitalist has been a long-time supporter of bitcoin. At a conference in October, Thiel said people are "underestimating" the digital currency.