Famed investor Steve Eisman is drawing the line on bitcoin, saying he will not invest in something he doesn’t understand.

Eisman, who’s primarily known for predicting the 2008 financial crisis as outlined in Michael Lewis’ book The Big Short, and providing the inspiration for Steve Carrell’s character in the subsequent film adaptation, said on Bloomberg Television Friday that he’s staying away from the highly volatile cryptocurrency as its value continues to swing wildly.

“Steve Eisman does nothing with ‘Big Bitcoin,’” he told Bloomberg Surveillance. “I stay out of it. I don’t understand it.”

Bitcoin was hovering at around US$32,000 on Friday, after seeing its value slide by about 12 per cent over the past week. The cryptocurrency had rallied to a record of nearly US$42,000 earlier this month.

The pullback is partially being fuelled by fears U.S. President Joe Biden may step in to regulate the cryptocurrency space. Eisman, however, said he’s yet to see any indication the newly-minted U.S. president will make a move to that effect.

“Is it possible that it’ll be regulated to a lower price? It’s certainly possible, but I haven’t seen anything that would cause me to think so,” he said. “I think the better part of valour here is to just stay away.”

Eisman said people who invest in the cryptocurrency are just speculating.

“My personal opinion is they’re buying or selling something that’s impossible to value,” he said. “It’s one thing to talk about what’s the U.S. dollar-yen valuation; when you’re talking about bitcoin, I think it’s more like talking about how many angels dance on the head of a pin. I don’t know how to answer the question.”