He noted that the bitcoin mania is reminiscent of the tulip bulb craze in the 17th century.
Banker Dimon was speaking at a banking conference in NY when he made remarks about the world's most prominent decentralized cryptocurrency.
But Dimon dismissed the entire market as "stupid" and went so far as to say he'd fire any Chase employee trading bitcoin.
Bitcoin is stored in a "digital wallet", allowing users to anonymously send and receive bitcoins and purchase goods, but does not involve banks and is not insured by the Federal Deposit Insurance Corporation, CNN Money said.
"The average price of bitcoin across global exchanges fell below $4,000 at roughly 3.15 UTC today, hitting a low not observed since September 10". "And both are unsafe", Dimonsaid. It's a harsh prediction considering Dimon's own daughter bought bitcoin.
The head of America's largest bank threatened to dismiss traders if they trade the cryptocurrency.
In the case of bitcoin, Dimon said he was skeptical that authorities would allow a currency to exist without state oversight, especially if something goes wrong. Blockchain is the technology behind bitcoin.
Dimon will also be speaking later Tuesday at the DeliveringAlpha conference in NY.
Dimon did admit there's a "limited market" for bitcoin: drug dealers, murderers, and countries like North Korea.
Mr. Dimon has indicated that the best argument in favor of bitcoin, is that it can be used in geographic regions in difficulty, or by thugs.
A crackdown in cryptocurrencies in China and ICOs (initial coin offerings) has been weighing on bitcoin and other cryptocurrency markets.