The argument against self custody. What’s your take?

I have a few friends and have read from a few people online that they don’t do cold storage. Some only keep their crypto on exchanges, and have read of, or had their own bad experiences with cold wallets before.

I’ve heard some people say that Coinbase is the “final boss” because if Coinbase goes down, at least for Americans, then there would be far bigger problems with the US, and thus global economy.

Where do you stand? I understand “not your keys, not your cheese.” But for those who choose to keep your crypto on exchanges, why do you do it?

I’d love any extra resources, or to hear the logic behind your reasoning.