There are plenty of examples of bank runs and other crises pre-regulation and pre-fiat currency, dating all the way back to the 1600s— that’s about as decentralized as you can get. If you want to argue that there’s something fundamentally different this time around, that’s fine, but I’d appreciate evidence rather than assertions.

In fact, the least problematic time in terms of bank runs appears to be the years of the highly-centralized Bretton-Woods system post-WW2 (1).

It’s also not like holding bitcoins yourself is entirely risk-free. You can accidentally expose your private key and have your money stolen or you can lose your private key and have it locked away forever. Either scenario means you no longer get to use your money, and any defense against one makes the other more likely; it’s a difficult balance to ask people to get right.

(1) https://en.m.wikipedia.org/wiki/Bretton_Woods_system