No, they're not stupid, they're rich to the point that it's hard for an ordinary person to even imagine - but you somehow come across as stupid because you think that Bitcoin is something that everyone should invest in. Apart from that, do you really think that Bitcoin should become something like digital gold, which in the next ten years will mostly be in the possession of those big companies - which, by the way, will keep them in custodial services because they are not capable of such a thing themselves?
If someone hacks such a custodial service, what implications do you think it will have on Bitcoin?
It is not recommendable to store bitcoins by any custodials and the advice is opposite, being your self custodian and being your own bank.
The future when bitcoin is mostly owned and stored by custodians that are centralized is not good with risk of hacks against those big custodians for example Coinbase that is chosen by many Bitcoin Spot ETFs so far as their custodian, is very terrible like a nightmare for Bitcoin market.
I don't wish anyone to lose their bitcoins but if they lost their coins, they are contributing more gifts to Bitcoin community.
As Bitcoin users, be your self custodians is the advice that is applicable now and in future.
Lost coins only make everyone else's coins worth slightly more. Think of it as a donation to everyone.