If you guys care about privacy while gambling better re-think before you make a deposit. below you can find a list of casinos which ask/ don't ask for KYC after winning big amounts
I agree with you here.If a casino enforces doing KYC after winning a good amount of money,they should be doing the same before money is being deposited on the account.This is a small gimmick every low graded untrustworthy casino will perform to steal from players as they know people are hesitant towards submitting documents online especially if gambling is not legal in their jurisdiction.
After KYC,there is another gimmick called "Security Procedures" which kinda works the same way.
I guess it is related to where the site's origin country or where the gambling site is situated in is as some governments really enforce this types of regulations well. There are certain amounts where if you go over will require the website to ask for KYC. I really don't think that it is a form of gimmick as this procedure is normal if the gambling site don't want to run into trouble with the government. Between me picking up a gambling site whether they require KYC to those who do not, I would always pick the former as they are the ones who are following the law, and if things goes south then we will have certain trail that can lead to them.