Nassim Taleb, the author of several well-regarded books on finance and risk and a onetime bitcoin fan, has published a draft paper explaining his recent 180 about the asset.

"[I]n spite of the hype, bitcoin failed to satisfy the notion of 'currency without government' (it proved to not even be a currency at all)," the self-described flaneur writes in "Bitcoin, Currencies and Bubbles," posted on his blog Sunday.

Bitcoin "can be neither a long or short term store of value (its expected value is no higher than 0), cannot operate as a reliable inflation hedge, and, worst of all, does not constitute, not even remotely, a tail protection vehicle for catastrophic episodes," Taleb goes on, with characteristic assertiveness.

It's a far cry from 2017, when Taleb wrote the foreword to "The Bitcoin Standard," economist Saifedean Ammous' book that made the case for the digital asset as a new form of sound money.

Bitcoin, Taleb wrote then, is "an excellent idea. It fulfills the needs of the complex system ... because it has no owner, no authority that can decide on its fate. It is owned by the crowd, its users. And it now has a track record of several years, enough for it to be an animal in its own right."

Taleb has since had a very public falling-out with Ammous, deleted his Medium post that contained the foreword and made his tweets private, meaning if you are not among the 743,000 people who already followed him on Twitter, you will now need his permission to see his posts. A new edition of Ammous' book is forthcoming with a foreword by MicroStrategy CEO and bitcoin bull Michael Saylor replacing Taleb's.

Contacted by CoinDesk Monday, Ammous, who can be as acerbic as Taleb, offered a two-word response to his erstwhile colleague's paper: "CRY HARDER."

Readers may judge Taleb's arguments for themselves by reading his full draft paper below.

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