Those are different things. Keeping up with your own private keys is a UX problem not a “who holds my money” one. People use bank for it’s benefits like savings or services like mortgages, it’s not because they don’t want responsibility. The matress money analogy doesn’t work since the reason people didn’t do that was because its tangible and therefore a risk it got stolen. Cryptocurrency is not tangible, nor do you actually hold any coins as it’s simply a ledger. The access to it, just like a pin for your banks, is just the UX problem.
Banks/institutions will exist for these services, not because people are scared of responsibility.