Legendary mathematician and “The Black Swan” author Nicholas Taleb, a one-time admirer-turned-detractor of Bitcoin, has denounced the world’s No. 1 cryptocurrency as a gimmick that resembles a Ponzi scheme.

Bitcoin is not a safe hedge against inflation and it’s too volatile to be an effective currency, Taleb told MSNBC Friday during a “Squawk Box” interview.

“Everybody knows it’s a Ponzi,” Taleb said. “Basically, there’s no connection between inflation and bitcoin. None. I mean, you can have hyperinflation and bitcoin going to zero. There’s no link between them.”

A Ponzi scheme is an investment scam that promises investors high rates of return with little risk. It uses new investors’ funds to pay earlier investors. The fraud eventually unravels when the flood of new investors, attracted by promises of easy money, dries up and there isn’t enough money to go around.

The biggest Ponzi scheme in history was pulled off by Bernie Madoff, who bilked thousands of investors out of tens of billions of dollars for 17 years. He was also a pioneer in electronic trading and chairman of the Nasdaq in the early 1990s. He died in prison on April 14, 2021.

Earlier this year, Taleb, a Lebanese-American bestselling author and former options trader, said he was getting rid of his bitcoin and tweeted that bitcoin is “a magnet for idiots.”

“I’ve been getting rid of my BTC,” he tweeted. “Why? A currency is never supposed to be more volatile than what you buy & sell with it. You can’t price goods in BTC. In that respect, it’s a failure (at least for now). It was taken over by Covid denying sociopaths w/the sophistication of amoebas” — Nassim Nicholas Taleb (@nntaleb) February 12, 2021

“#BTC is a magnet for idiots.” https://t.co/pkiA3HaAj9— Nassim Nicholas Taleb (@nntaleb) February 14, 2021

An academic researcher, professor and former derivatives trader, Taleb taught for 12 years at New York University School of Engineering. His work concerns randomness, probability, and uncertainty.

He is credited with coining the phrase “black swan” to mean an unpredictable, rare, and catastrophic event. In his 2007 bestseller, “The Black Swan,” Taleb wrote about highly improbable events and their potential to cause catastrophic consequences.

Taleb wasn’t always a Bitcoin critic but he told CNBC he was “fooled by it initially” because he thought it could develop into a currency used in transactions.

“It’s a beautifully set up cryptographic system. It’s well made but there’s absolutely no reason it should be linked to anything economic,” he said. “Something that moves 5% a day, 20% in a month — up or down — cannot be a currency. It’s something else.”

Taleb said he bought into Bitcoin, “… not willing to have capital appreciation, so much as wanting to have an alternative to the fiat currency issued by central banks: A currency without a government. I realized it was not a currency without a government. It was just pure speculation. It’s just like a game … I mean, you can create another game and call it a currency.”

Bitcoin could go to $1 million and it wouldn’t change his argument, Taleb said. “These gimmicks, you have bitcoin today. You may have another one tomorrow. They come and go, and there’s no systematic link between them and the claims they make,” he told Squawk Box.

                                     Listen to GHOGH with Jamarlin Martin | Episode 74: Jamarlin Martin                                              Jamarlin returns for a new season of the GHOGH podcast to discuss Bitcoin, bubbles, and Biden. He talks about the risk factors for Bitcoin as an investment asset including origin risk, speculative market structure, regulatory, and environment. Are broader financial markets in a massive speculative bubble?

Taleb is hardly alone in ripping bitcoin. U.S. Treasury Secretary Janet Yellen said in February that Bitcoin is used “often for illicit finance. It’s an extremely inefficient way of conducting transactions. And the amount of energy that’s consumed in processing those transactions is staggering. But it is a highly speculative asset, and I think people should beware.”

But Bitcoin has growing support from market bulls such as Tesla CEO Elon Musk, who bought $1.5 billion worth of bitcoin and said the electric car maker would start accepting it as payment.

Mike Novogratz, chairman of Galaxy Digital Holdings, expressed confidence in Bitcoin. “That existential threat of Bitcoin not being real is gone,” he said. “Every institution in the world is participating and so it’s an asset class.”