Keep in mind as a gambler who gambles online must be ready to expose himself or herself to KYC it's unavoidable requirements from casino site.
I guess he doesn't need to move to another casino, especially if he is used to using big money to gamble because maybe other casinos won't allow him to withdraw winnings without doing KYC.
Casinos may pay attention to you if you spend big money and maybe they will also ask you to do KYC.
For reputable casinos, they can simply ask their users to verify their accounts because if there is any suspicion, it will be related to their reputation.