“My best guess is that in the long run, the technology will thrive, but that the price of Bitcoin will collapse.”

Bitcoin’s price has exploded over the last two years, and has climbed more than 350% since the start of 2017.

The cryptocurrency’s rapid ascent, and the cottage industry that has grown around it, have both galvanized investors’ interests and elicited their fair share of criticism.

A number of top Wall Streeters have recently have expressed concerns about Bitcoin. JPMorgan CEO Jamie Dimon called it “a fraud” that is “worse than the tulip bulbs,” referring the 17th century Dutch tulip-mania bubble. BlackRock Chairman and CEO Larry Fink, meanwhile, told Bloomberg News that “it just identifies how much money laundering there is being done in the world.”

Bitcoin and other digital currencies’ transactions are done anonymously. They aren’t monitored by central banks like, say, the dollar or the euro. In his piece, Rogoff suggests that if Bitcoin was no longer anonymous and more regulated, then its price might not be sustainable.

“Were Bitcoin stripped of its near-anonymity, it would be hard to justify its current price,” he wrote. “Perhaps Bitcoin speculators are betting that there will always be a consortium of rogue states allowing anonymous Bitcoin usage, or even state actors such as North Korea that will exploit it.”

He added that central banks could also create their own digital currencies and then use regulation to “tilt the playing field until they win.”

“The long history of currency tells us that what the private sector innovates, the state eventually regulates and appropriates,” he wrote. “I have no idea where Bitcoin’s price will go over the next couple years, but there is no reason to expect virtual currency to avoid a similar fate.”

The cryptocurrency was up by 2.5% at 4,718.5098 against the US dollar at 2:44 p.m. ET.