Banks exist because most people don’t want to stuff cash under a mattress or memorize seed phrases. For 99% of daily life, convenience beats ideology. And yes, money in the bank is part of a social contract: they use it, you access it when you want, the world keeps spinning. The fee is the price of modern friction
If you trust banks, it’s probably because you’ve never hit the hard edge of “your money isn’t available”. Ask anyone from a country that’s had a banking crisis or a currency freeze. This “take your cash anytime” is only true until it’s not. So yeah, banks are business, and business runs on trust. But isn’t the whole point of Bitcoin and self-custody about not having to ask for permission?
I still highly doubt it's about the security or safety of it, like mentioned before, if that was the only reason, we would have a "vault" company instead of banking like back in the day. The first banking business' started because of vault was needed, all those big soldiers who went and conquered, returned, and they had much gold from spoils, and mainly the lords and kings, so they needed a vault.
But, we need to remember that we are seeing something much worse with baking doing more than that. So that means, we do not need it as a vault only, we need it for transactions, how are you going to move 150k dollars if you didn't had banks? You couldn't, all cash that much money would be stupid, so it's smarter to just move it via bank.