“Dr. Doom” isn’t mincing his words when it comes to the crypto boom and bust.

Nouriel Roubini of Roubini Macro Associates said Bitcoin is the “biggest bubble in human history” and this “mother of all bubbles” is finally crashing, in an interview with Tom Keene and Francine Lacqua on Bloomberg Television. Bitcoin dropped below $8,000 Friday, a 60 percent tumble from its peak of $19,511 on Dec. 18.

Now Bitcoin crashing below 8000, headed towards 7000. Down 60% from the peak, 40% in a month and over 10% today. The Mother Of All Bubbles And Biggest Bubble in Human History Comes Down Crashing. pic.twitter.com/jfILcrNNXA

— Nouriel Roubini (@Nouriel) February 2, 2018

It isn’t just Bitcoin, Roubini added. There are more than 1,300 cryptocurrencies or initial coin offerings, and “most of them are even worse” than the largest digital token. These constitute a “a bubble to the power of two or three,” he said.

Blockchain has “been around for 10 years, and the only application is cryptocurrencies, which is a scam,” the New York University economist added.

In another salvo aimed at crypto bulls, Bitcoin is an “environmental disaster,” he said, citing its soaring energy costs.