Some casinos do not pay the fee, while others do. However, in order to process the transaction, casinos who did not pay to broadcast withdrawal transactions deduct a small percentage from the withdrawable amount not from main balance to be clear that they only pay network fees nothing more.
If a casino establishes that the person must pay their fee it is not bad, it is something that seems decent to me, in fact most casinos are like that, I understand many of us who say that hopefully they will not charge at the time of withdrawal, however the little that they charge from the balance is something that is not representative, that is where the casino's profit as such is directed, sometimes we do not give importance to the casinos that do pay the fees, but when the BTC network is congested is when this type of casinos are most useful.