Max Levchin, co-founder of PayPal, has revealed that he is a big fan of blockchain technology, but is still making up his mind on bitcoin.

Speaking to CNBC during a Breakthrough Prize award ceremony in Silicon Valley on Sunday, Levchin said that blockchain will find use cases across different industries, is a “brilliant mathematical idea” and “interesting commodity to speculate on.”

However, on the cryptocurrency, he said:

“It’s not clear to me whether bitcoin itself is the great long-term investment.”

It’s yet to be seen whether bitcoin is a currency “or just a way to make money fast,” he added.

Levchin’s stance on bitcoin is notably different that of fellow PayPal co-founder Peter Thiel, who told CNBC in October that he believes bitcoin has a promising future, though he was skeptical of most other cryptocurrencies.

“It’s like a reserve form of money, it’s like gold, and it’s just a store of value. You don’t need to use it to make payments,” he said at the time.

Those who are criticizing the cryptocurrency are “underestimating” it, Thiel argued.

PayPal image via Shutterstock