It's not that difficult to get a non custodial wallet, write out your seedphrase and store them in a secure place is it? So why would you want to risk the safety of your funds in the hands of centralized platforms?
""NOT YOUR KEYS, NOT YOUR COINS" non custodian wallet are good storage for coins".
It's not enough.
Choosing good wallets to use must have two main criteria: non-custodial (or aka self-custodial) and open-source (aka reproducible) and you only mentioned about non-custodial but forgot about open-source.
It's not hard to get a non-custodial and open-source wallet as it is free to download, verify and install to use without any fee. People either don't know about open-source, non-custodial wallets or just believed in custodial wallets or close-source non-custodial wallets.
It's about how you can verify those open source self-custodial wallet. We don't like close source as obviously we don't know what's inside, we don't trust we verify. So there is a big possibility that there could be a back door program put by the programmer and it's like a switch that he can turn it on anytime without us knowing. We won't point a good self custody wallet, for sure the OP and others might have known what wallet is it already. And gradually after learning this self custody wallet and their Bitcoin are growing, then that is the time that you move to hardware wallets, same criteria, it should be also open source.