Tim Berners-Lee, the inventor of the World Wide Web, called cryptocurrency “dangerous” and likened it to gambling in an episode of CNBC’s “Beyond The Valley” podcast published last Friday.

Discussing the future of the web, Berners-Lee said digital currencies are “only speculative” and compared it to the dot-com bubble, in which internet stocks, often without a solid business behind them, were highly inflated.

“It’s only speculative. Obviously, that’s really dangerous,” Berners-Lee told CNBC. “[It’s] if you want to have a kick out of gambling, basically.”

“Investing in certain things, which is purely speculative, isn’t what, where I want to spend my time,” he added.

Berners-Lee said, however, that digital currencies could be useful for remittances if they’re immediately converted back into fiat currency when they’re received.

The British computer scientist is credited with inventing the World Wide Web in 1989. But Berners-Lee has been dissatisfied with the way his original vision for the web has panned out. Alongside John Bruce, Berners-Lee is looking to reshape the future of the internet through his startup Inrupt, with the aim of giving people more control of their data. Both spoke to CNBC’s “Beyond The Valley” in a wide-ranging interview about the future of the internet.

Many proponents have spoken about the future of the internet in terms of Web3, a catch-all phrase with no clear meaning. But proponents often say this version of the internet runs on blockchain technology which first came into existence with the cryptocurrency bitcoin. Web3, some say, is a decentralized internet that takes away some power from giants like Facebook and Google.

But Berners-Lee said the future of the internet is “Web 3.0,” which he distinguishes from Web3. Web 3.0 is his own proposal for reshaping the internet.

“It’s not blockchain,” Berners-Lee said, suggesting the technology isn’t fast or secure enough.