Professor Nouriel Roubini, the economist nicknamed “Dr. Doom” for predicting the housing bubble crash of 2007-2008, who is one of the biggest crypto bears in the world, called the blockchain “a glorified Excel spreadsheet” at yesterday’s panel on cryptocurrencies at the Milken Institute Global Conference 2018 in Beverley Hills, California. Naturally, this didn’t go down well with the Bitcoin (BTC) and blockchain advocates at the panel, and the resulting “cryptobrawl” was by all reports quite entertaining.

Roubini, who teaches economics at New York University Stern School for Business, and who is quite famous for his generally bearish views on financial markets in general and blockchain/cryptocurrencies in particular, had previously launched several attacks on Bitcoin — calling it “a Ponzi scheme”, a “lousy” store of value, and “a conduit for criminal/illegal activities” and “the biggest bubble in human history” — and the blockchain, calling it “one of the most overhyped technologies ever.”

And, sitting at a panel, with Alex Mashinsky — founder of Celcius Network, an Etherium-based peer-to-peer platform for lending/borrow (based on the idea of using your crypto holdings as collateral) — and Bill Barhydt — founder and CEO of Abra (the company that developed the Abra mobile app for cryptocurrency trading) — Roubini didn’t hold anything back.

“All this talk of decentralization is just bullsh*t,” said Roubini, which Mashinsky countered with “Everything you just said is irrelevant”; as for Barhydt, he said that he didn’t “even know where to begin.”

After the moderator, Anna Irrera, who is a Fintech correspondent for Reuters, asked for a timeout to let the parties cool off, another panel participant, Brent McIntosh, a lawyer who works for the U.S. Department of the Treasury, offered to “step in and regulate this panel.”

When Mashinsky said crypto assets would let people bypass banks, Roubini replied “You’re just making stuff up.”

Roubini also called Bitcoin a “bubble” and said that people who “arrived late to the party are the suckers.” After hearing that Roubini had never even bought a single bitcoin, Mashinsky, told Roubini: “Why don’t you buy one coin and then tell us how it works.” And Barhydt made fun of Roubini by saying “It’s like a horse salesman saying we don’t need combustion engines.”

Despite Roubini’s extremely bearish attitude towards cryptocurrencies, he is a little less critical when it comes to blockchain technologies and can see some use cases for them: “Ultimately, blockchain’s uses will be limited to specific, well-defined, and complex applications that require transparency and tamper-resistance more than they require speed — for example, communication with self-driving cars or drones.”