Many websites we visit and submit our personal information to are most times because we trust them, you can’t just give your personal details to a website you just come across without knowing of their virility with such informations. It may not be easy to know the site that may have sold your data out, but it is also much possible that it may be the most recent one you’ve uploaded your personal information to especially if you have some reservations about them at the time of even registering and providing this personal details. That is why you only give your personal info to where is trusted and have good reputation of trust from existing users.
That's not always the case. Some people doesn't care about these things like KYC and will give out their information when required/asked/needed. While others may hesitate, but still do the same, because they need to use that particular site/service. Tbh, I personally don't trust any centralised exchages but I have accounts that are fully KYC verified. I don't have any other alternatives to do my transactions, so I'm forced to use these (not because I trust them, I don't), not because I trust them but I don't have any other choice.
I have one regular practice, and that is to always hand out my kyc documents for verifications immediately after my account creations, this help me to overcome alot of stress along the way since i dont know which casino i have the luck of hitting my first 1000x multiplier that make me the jackpots winner and want to withdraw on $100Ks without problems.
So for sure anyone can do that as long as you have nothing to hide and you trust the casino, making sure you give your documents to only reputable casinos, this will definitely make alot of sense solving all this KYC issue's.