Economist Nouriel Roubini sharply criticized cryptocurrencies on a panel at the Milken Institute Global Conference yesterday, Bloomberg reported May 2. Roubini said that “all this talk of decentralization is just bulls**t.” Panelist Bill Barhydt, who has worked on cryptography for the CIA , responded,“I don’t even know where to begin.”

Roubini has become known in some circles as “Dr. Doom” for his canny prediction of the 2008 Financial crisis. He proceeded to censure cryptocurrencies, arguing that digital coins are not a store of value, and face scalability issues in comparison with centrally intermediated payment systems.

Another panelist Alex Mashinsky, CEO of crypto lending pool Celcius Network, suggested that crypto assets have the potential to free individuals from the grip of financial institutions. Roubini said, “You’re just making stuff up.”

“Why don’t you buy one coin, then you can tell us how it works,” Mashinksy answered.

Brent McIntosh, who currently serves as general counsel for the U.S. Treasury, tried to pacify the discussion, suggesting, “I may need to step in and regulate this panel.”

Roubini has previously predicted that looming regulations would be “the nail in the coffin” for “the gigantic speculative bubble” of Bitcoin and other digital coins:

“I think that more and more countries will start to make cryptocurrency exchanges illegal like China did. New regulations will be adopted. So, this will find its end.”

Cointelegraph ran a twitter poll last winter to gauge the crypto community’s response to his notoriously grim forecast: