Nothing on this world is unhackable and we should really bare it up into our minds no matter how reputable or popular it would be there would be always those probabilities and that's why we do keep on
seeing these kind of situations just because there's no such thing about perfect security which does as a user then you should really be aware of that.We've seen various exploits which it did really
result into huge loss of funds of a certain gambling site because of those lapses and this is where security does continue to improve overtime.So far there are
no huge hacking or exploits on recent years not like into those years of the old.
Sadly the reality is even worse than that, everything can be hacked, it does not matter how complex is the protection of a piece of software or a website, hackers can always find a way to hack it with enough time, this is why opening up a casino is such an expensive business as not only you need a lot of capital to begin with but a great deal of the money will always go towards securing your website, because the moment you stop investing in this is when hackers will have all the time in the world to exploit the casino.
You have a point, but expensive budget doesn't guarantee you anything, because hackers can hack whatever they want if they want to (pertaining to professional blackhat hackers). This might be off-topic but even Binance and other big exchangers got hacked already, sometimes hacker return the funds, sometimes they don't. My point here is no software or system is safe.
They return their funds because they are traceable, in the case of Casinos they are quick to find vulnerabilities and big casinos are good at doing that, that is why I prefer and highly recommended playing on big casinos they can do refund they have top-level security when it comes to casino security funding and financial capability is a big factor.