Not just only Bitcoin withdrawal, even coins with very low transaction fee, isn't this robbery? If you just signed up on a centralized exchange, you can pretend as if you want to withdraw, to know how much the gas fee costs, but on online casino, you will see this only after you have enough wins or funds for withdrawal.
I guess it boils down to business, the high transaction fees are going to fluctuate though, as you can see in the mempool right now, ~50 sat/vB for a low priority and then ~79 sat/vB if you want your transactions to be included in the next block.
So that is expensive again, it fall to like ~15 sat/vB, but here we go again and it could increased this weekend again.
But I do agree in your sentiments, the best case scenario for us is that casino's not charging as transaction fees as it is a burden for us specially if we have lost so much money already to them.