As I've noted before on HN the entire concept of people being able to manage their own wallets flies against everything we know about people. People forget stuff, make mistakes, and lose things. The margin of error for a wallet is tiny. It's not rare for crypto forums, twitter, etc to prescribe completely ridiculous processes and systems for securing wallets, backing up seed phrases, etc. There's an entire cottage industry built around people etching their seed phrases on steel plates for people to (I'm not kidding) bury them like they're gold in the 1800s.
Plus funds in a wallet require extra steps when you want to trade on an exchange (extra costs via gas, time, possible errors, etc). The use cases for crypto are so minimal for the general population one could argue it's only survived this long through making trades on exchanges - to what essentially amounts to gambling. You can't gamble with funds in a wallet which defeats the entire purpose of crypto for the vast majority of the "users" in the space.
Plus funds in a wallet require extra steps when you want to trade on an exchange (extra costs via gas, time, possible errors, etc). The use cases for crypto are so minimal for the general population one could argue it's only survived this long through making trades on exchanges - to what essentially amounts to gambling. You can't gamble with funds in a wallet which defeats the entire purpose of crypto for the vast majority of the "users" in the space.