The moment you asked for withdraw from casino, your funds are proceed and you aren't able to gamble, i.e. when you click the withdraw button, you are no longer to gamble, so, there is no problem in this case I guess and it has nothing to do with the time of transaction process and then confirmations on blockchain.
Btw there are some solutions for these kind of users even without withdrawing:
1. Ask to freeze their account for a while (you won't be able to unlock it even if you request).
2. Some casinos offer additional wallet where you can lock your funds.
Btw that's the personal problem that needs to be treated, it means that you are addicted to gambling and like other kind of addictions, this one can ruin your life.
The main idea is that gambling and exchanges are different. If you have money in an exchange and you are not getting it right away then what are you going to do? Like you can't gamble it and then lose it, it is there and it will come, plus after you already confirm withdrawing even if it is not coming just yet, it is not tradable in most of the cases as well.
This is why I was saying that casino business is a bit different because if you cannot withdraw your money right away, then you may end up gambling with it and lose it all. So in an exchange it is "I have 100 bucks in it, I withdrew all 100, they haven't sent it yet, but it is there and coming and I can't do anything with it" , whereas in a casino you could have "I withdrew 100 bucks from this casino, they didn't do it, they didn't had hot wallet so I ended up gambling with it and lost it all", it is possible and that's the problem.
Is there any casino that has constantly empty hot wallet? And because of empty hot wallet you can't click on withdraw button? What I say from my experience (and I was working in one online casino), I can say that your funds (in cases that I know, haven't had different experience), from the moment you click on withdraw, it doesn't matter whether hot wallet is empty or not, the amounts of coin that were meant for withdraw are immediately locked. Have you ever received message from casino that they can't proceed withdrawal because they don't have money in hot wallet? Idk, if there exists such casino, you better not gamble in those ones. There are a lot of casinos where you won't ever hear about that kind of problems, better do some research and don't play on poor casinos that doesn't properly manages the budget.