It's better if you are going to check each of the bookmaker's terms and condition since you said you are going to deposit and bet high stake some of them might ask you KYC.
And some of them might confiscate your deposit if you violated any of their terms so be careful and check everything before depositing.
All of the Casino has the right to freeze / block your money if you are violating there terms but they are not allow to confiscate your balance unless your account abuse there giveaways or exploit a bug on there Casino that result to your current balance but Casino is not allowed to confiscate your deposit money. They will freeze it but you can still claim it after sending KYC documents as AML requirements for dealing on this kind of situation.
I suggest staying away to all Casino that offers fiat deposit because they are the casino that has a critical license in terms of KYC for high rollers.
Most of the trusted sportsbooks have their gaming license and so it is hard to find one that don't require KYC if you are a high roller. It is hard to trust a site if they are not considered reputable in the forum because you can lose money without a fight. So for me, it is better to play on a casino requiring KYC, but at least, you are confident that you will not lose money for nothing. You can also ask help from this forum if you feel you are wrongly accused by the site.