Nicholas Nassim Taleb has reversed his stance on bitcoin.

The “Black Swan” author said in a recent paper that the largest cryptocurrency by market cap has failed to satisfy the notions of it as a currency without government, a hedge against inflation and as a safe haven investment.

“Few assets in financial history have been more fragile than bitcoin,” he said.

The Lebanese-American Taleb had previously spoken more favorably on bitcoin, particularly on its potential to help people circumvent capital controls in markets that rely on them to manage their exchange rates. He called it “the first organic currency,” in the foreword of “The Bitcoin Standard” in 2018, and “an insurance policy” against government control over currency.

In his recent paper, published in late June and titled “Bitcoin, Currencies, and Fragility,” Taleb says bitcoin is worth “exactly zero” partly because it requires a sustained amount of interest to maintain it.

By contrast, “gold and other precious metals are largely maintenance free, do not degrade over an historical horizon, and do not require maintenance to refresh their physical properties over time,” he said.

Bitcoin was created in 2008 and has always been notoriously volatile, though the Covid-19 pandemic year is the first time it has experienced such extreme volatility in the face of a global economic crisis.

Taleb noted that in March 2020 bitcoin dropped further than the stock market and recovered with it “upon the massive injection of liquidity.” That’s “sufficient evidence that it cannot remotely be used as a tail hedge against systemic risk,” he said.

He also added bitcoin tends to respond to liquidity and that it’s unclear what would happen if the internet experienced even a regional outage, particularly if it took place during a financial collapse.

Taleb noted bitcoin “has maintained extremely high volatility” of between 60% and 100% “throughout its life,” though that doesn’t mean a cryptocurrency can’t “displace fiat” — that is, money backed by the government that issues it but not backed by a physical commodity like gold.

“It is indeed desirable to have at least one real currency without a government,” he wrote in his paper. “But the new currency just needs to be more appealing as a store of value by tracking a weighted basket of goods and services with minimum error.”

People also constantly conflate the success of bitcoin as a digital currency with the success of bitcoin as a speculative investment. To be a currency would require it to have some stability and usability, Taleb said.

The price of bitcoin was about $32,000 Tuesday morning and has been hovering between $32,000 and $36,000 for about a month, after briefly touching $40,000 in mid-June.

Cryptocurrency exchange data show bitcoin trading fell more than 40% in June of this year, according to CryptoCompare. In the same month, the price of bitcoin hit a monthly low of $28,908.

Still, June 2021 volume ranks in the top five months of volume recorded ever, according Kaiko data.