Making big bets on speculative assets with retirement money is something most advisors warn against, but Bitcoin fever is prompting all sorts of puzzling decisions.

For 67-year-old Dennis Gartman, the longtime publisher of a namesake daily investing newsletter and television commentator, that was putting a volatile stock called Riot Blockchain Inc. in his very own retirement account. The wager is proving to be painful.

The stock lost a third of its value on Feb. 16 after CNBC broadcast an investigative story on the biotech-company-turned-blockchain-startup. The Suffolk, Virginia-based commodities trader and economist might have been hoping to strike it rich and retire early, but he may end up working a few extra years now.

“Friday was one of the worst days we have suffered through in a very long while,” he wrote in the Gartman Letter on Tuesday. “We were long of a sizeable position in a blockchain focused company that was the victim of a CNBC expose, which sent the shares down more than 20 percent and which sent us ‘down’ for the year to date, having been up about 6 percent previously.”

The firm announced in October that it was rebranding itself from Bioptix Inc. to Riot Blockchain after years of lackluster stock performance and minimal revenue growth, a move that led the shares to more than quadruple. The euphoria didn’t last.

“Lessons have to be learned again and again and again it seems,” wrote Gartman, who told CNBC less than two months ago that Bitcoin is nonsense. “Or at least we apparently have to learn them over and over and over again.”

This article was provided by Bloomberg News.