There is a purpose for having KYC in some gambling platforms and that is to avoid money laundering. Anyway, it may be used to launder money but cryptocurrency being used in illegally activities are not much anymore compared before. KYC stops gamblers to gamble where they are only going to gamble and when a lucky gambler won then tried to withdraw but KYC is needed then it's a bad start. No one would want that even if you are sure that you didn't launder money.