I'm sure if you bet at a licensed casino and have rules for KYC but right now you haven't been asked to fill out KYC, when you get a big win, you will immediately be asked to fill out KYC so you can withdraw all your big wins.
It always seems sketchy when your asked to go through KYC after a big win, I don't like the practices as well but, playing on the casino or sportsbook with hopes for big wins already means, you deal them some level of trust not just to leave up to the end of there bargain but, for them to be able to protect your identity as well.
Hence, it shouldn't be too difficult to oblige when required. You could see it for a final verification before withdrawal to ensure your wins aren't been hacked by an impostor.
But that's how it is because the government also supervises the licensed casinos so they have to follow the regulations from the government. If your winnings aren't as big as everyone else's or under $100, the casino will let you withdraw the winnings. So get ready to do KYC. The casino may ask you to do KYC if you get a big win.
But I think if the casino is reputable and we always use it, it means we already believe that the casino can provide security for the data we submit to them so we can do KYC safely. And if you really don't like those ways, maybe you can move on to another casino that doesn't ask you to do KYC. But everything will have a risk behind it so we should understand the risks and be able to choose what is good for us.