MicroStrategy founder Michael Saylor's suggestion that crypto users should use major banks to hold Bitcoin has been called "insane" by Ethereum co-founder Vitalik Buterin, adding to growing backlash from the crypto community.

“I will happily say that I think Saylor's comments are pure insanity,” Buterin said in response to an Oct. 22 post on X from Bitcoin custody firm Casa's chief security officer and cypherpunk Jameson Lopp, who was extolling the virtues of self-custody.

Buterin said Saylor appeared to be “explicitly advocating a regulatory capture approach to protecting crypto,” such as investment managers BlackRock and Fidelity holding the asset with “all the legislators and watchdogs invested in those entities.”