At the same time we shouldn't also ignore that self-custody comes with its own challenges, I mean we heard and seen cases where people lose their wallets and their seed phrases. Buut even with those risks, one thing is still certain which is that once you give up your keys, you have given up your control. To me, that’s enough reason to say "YES to self-custody, and NO to custodial platforms."
Self custody is better and only people who don't care about their money keep 100% their asset in custodial wallet.
The concern that you mentioned about losing seed phrases and so on is real, but it can also be prevented easily. With just having backups, you can already avoid this and reduce the chance of losing seedphrase to less than 99%. What it takes is just multiple hardware wallet and multiple encrypted seed phrases.
On the other hand, custodial wallet got their problems too, such as losing money over sending on the wrong network,
etc whileand so on. While the address is the same and private key is the same, for some reason the party that's responsible for the custody just don't want to retrieve it for you. This is the truth that people often ignore or just don't want to know. Ignorance is bliss I guess.