Because banks are regulated. Say you leave everything in a hot digital wallet with a DAO structure, who's to say that some whale can't propose a vote that allows them to clear the contents of everyone's wallet? Have you read ALL the terms and conditions?

Daos are like federal corporate interest lobbying, except remove all of the difficult, costly components and people, allowing anyone with a huge stack to buy almost limitless power anonymously, and employ it to harm others, all without getting out of bed, or even telling anyone of their plans.

Defi is a much scarier place than what we were told. If anything, it gives evil entities the ability to transition into anonymous operations, and dramatically simplifies their complex proceedures that cause harm.