Nouriel Roubini, a professor of economics at New York State University known as “Dr. Doom” because of his seemingly permanent bearishness regarding the markets, is once again denouncing blockchain and cryptocurrencies as “the mother of all bubbles.”

Per an article Thursday in Bloomberg:

“It is clear by now that bitcoin and other cryptocurrencies represent the mother of all bubbles, which explains why literally every human being I met between Thanksgiving and Christmas of 2017 asked me first if they should buy them.”

Roubini said crypto-proponents are turning to blockchain, the underlying tech that cryptos run on.

“The new refuge of the crypto scoundrels is blockchain, the technology underlying crypto that is now alleged to be the cure of all global problems, including poverty, famines and even diseases,” his statement reads.

Citing scalability issues and a lack of decentralization, the bitcoin skeptic adds blockchain technology is “nothing better than a glorified spreadsheet or database.”

Scalability is the ability of cryptos to process more transactions, which has been a significant roadblock to real-world usage.

Bitcoin BTCUSD, -5.14% can process around five transactions per second, and ethereum, the popular smart-contract based blockchain, can process anywhere between 10 and 15 per second, whereas companies like Visa V, -0.59% and Mastercard MA, -0.41% can handle more than 5,000 per second.

Roubini also isn’t a fan of the crowdfunding tools that crypto-related ventures use to raise money.

“[H]undreds of other cryptocurrencies are invented every day, alongside scams known as initial coin offerings, which are mostly designed to skirt securities laws,” he said.

Roubini was set to speak more about Bitcoin with Peter Van Valkenburgh on Thursday morning.

Editor’s note: What are your thoughts on the crypto markets? Is Roubini correct? Or is he just being negative for the sake of being negative? Share your thoughts in the comments below.