• "Dr. Doom" economist Nouriel Roubini told Yahoo Finance Live that 90% of crypto is a scam.
• He described the stricken industry as a "total real-bubble Ponzi scheme that is going bust."
• The former NYU professor called most crypto execs "crooks" and said FTX founder Sam Bankman-Fried is not an outlier.

Economist Nouriel Roubini, also known as "Dr. Doom," blasted the embattled cryptocurrency industry on Wednesday.

"Literally 90% of crypto is a scam. A criminal activity," Roubini, who is known for his dire global economic predictions, said on Yahoo Finance Live. "A total real-bubble Ponzi scheme that is going bust."

Vulnerable retail participants have lost tons of money from investing in digital assets, he said, with traders jumping into bitcoin during its all-time highs. The crypto has since plunged almost 70% from its peak in November of 2021, according to Messari.

"You have to stay away [from crypto.] You have to absolutely stay away," Roubini said. "Most of these people belong literally in jail. Literally, they're all crooks."

Speaking outside the World Economic Forum in Davos, Switzerland, the former New York University econ professor also took aim at disgraced founder Sam Bankman-Fried and his failed crypto exchange FTX. 

"FTX and SBF are not an exception — they're a rule," he added.

Bankman-Fried pleaded not guilty to eight criminal counts earlier this month and is accused by US prosecutors of orchestrating a years-long scheme to defraud investors. FTX filed for bankruptcy in November after his crypto exchange lost at least $8 billion of customer funds.

Roubini, one of the first experts to call the 2008 crisis, has been sounding other alarms lately too, including a stagflationary debt crisis.

And last week, he warned the Federal Reserve will wimp out on its inflation fight, and predicted gold is the best protection for investors as volatility batters the economy.