I don't mind getting a bonus/cashback for doing KYC, but this seems kinda sketchy. KYC is supposed to be mandatory, why would a casino offer bonuses for the gamblers conducting KYC? Getting various incentives for ID verification would make me suspicious, but you can implement it as a feature, that would make your casino stand out from the competition. Try it and see the results.
How do you describe a "painless KYC"? I wonder how "painless" the ID and Address verification would be, if I had several thousand dollars worth of crypto in my gambling account. I always try to withdraw small amounts of crypto from my gambling accounts, because I have the suspicion that the casino might scam me, if the customer support finds out that I have a big balance in my account.