Can you also include reference to prove your claims that this sites will ask for documents when you will win big?

Although sharing your personal documents with trusted sites might not hurt your personal privacy.

how do you know about all these information? i play on primedice before and i saw a guy withdrawal so many bitcoins and he can withdrawal easily without problem and kyc. i think gambling site use kyc only for a player that had a suspicious activity on their account and for withdrawal a big money like 50 btc and more.