in fact those are one of the things that are always handled in Casinos, the issue of kyc that nobody likes, but what you say is very true, if you are an average player, who has decent earnings that are not so high, because the kyc is not so radical, but for the whales they do ask for much more documents and it is something normal, since you bet with more money they agree to the Casino's demands because they require everything they can provide, I imagine this too which is for the protection of the players themselves, although as I said before, I am not very given to the kyc, nor for the average player or whale.
They demand documents from whales in order to prevent all that money laundering aspects and follow the regulations also but asking for more and more documents and ending up privacy completely which I would fear as big whale also as there are some casinos going too much hard but Rollbit is good option for them.
I think money laundering would have been the biggest ever trouble if KYC wasn't ever asked. I am not saying it has to be asked beforehand or something, it could be asked later on as well, but the fact that it is not even asked at all? That's not possible because in that case places could just spend tens of million dollars depositing here, and yes that's a big risk, what if they can't take it back, but if they try with smaller amounts first they could get some trust and then they would just launder that money forever.
I wouldn't want that type of risk on any casino and that is why it is better to have KYC, even if they do it, at least KYC there to protect them.