Perhaps, the money launderers already know that casinos are now tightening their rules by asking their users to do KYC, including those who use big money to gamble. Casinos want to protect their business from the illegal activities carried out by these money launderers, so they feel compelled to implement KYC on big gamblers.
Well, perhaps it makes some big gamblers who have nothing to do with illegal activities feel uncomfortable, but they have to follow the rules of the casino. Meanwhile, money launderers feel their movements have become increasingly limited with KYC. And there is a possibility that they will ask someone else to do KYC so they can use the verified account freely.
Some of the most popular casinos that have large bankrolls have implemented a KYC verification system for all customers who make transactions with large amounts of money so that criminals or perpetrators of illegal acts such as corruptors or embezzlers who want to launder money in order to eliminate evidence have had difficulties and of course have succeeded more on tap.
But it's true what you said that some of them may buy someone's personal data to complete KYC verification and of course that way the perpetrators of these illegal actions can still carry out their actions.
Every casino must find another way that can make it more difficult for money launderers and that way each casino can avoid problems regarding money laundering.