Normies manage their house keys just fine. Obviously crypto keys come with different challenges but that's a UX problem. People losing their house keys is not generally an Earth shattering event. Losing a crypto key doesn't have to be either.

A wallet is easier to lose than a bank vault, but it also holds less money for the same reason. Crypto keys can be designed the same way, with high importance keys managed by safer means like m of n schemes mixed with traditional "hard" storage in geographically distributed safe deposit boxes or whatever, while less important keys can be treated in a more relaxed fashion.