We? There is no system that is 100% secure by default, the devs still have a responsibility to audit and check their system regularly, to ensure there are no critical bugs that can be exploited. This is the reason why open source and well-reviewed wallets are recommended, not because they are immune to breaches, but because they can be easily identified and patched.
Let's not forget that the first reason why self-custodial wallets are recommended is because its users control their keys and they cannot be locked out of their funds. However, how their devs manage the software and fix vulnerabilities is another thing.
Reports have shown that hackers are using AI technology to identify lapses in these decentralized systems. Developers are now going a step further by adopting this new technology to review and verify code. The system is far from perfect, but it is safer than someone freezing your funds for one excuse or another.
The truth is that, most of the victims of these incidents are already aware of the consequences of putting money in such platforms and just as you already said, they believe so much in the security of those platforms but with all these recent hacks I hope they would have a rethink and try to do the right thing.
There are several better wallets to use and that is why I can't and don't want to believe that, there are people who make deposit to prediction market wallet with hope to holding it and it playing games with the deposit which is just insane to me.
Some people don't want to take responsibility. They want to keep and use Bitcoin the same way they use their fiat bank accounts. Anyone who is using an exchange, casino, or prediction market account as their bank might end up regretting their actions.