Ok, suddenly the casino you're playing asks you for proof of income to be able to withdraw your winnings and to keep your account in good standing, your bankroll every month is $500 and you provide proof of salary that you are making $500 net every month, will they accept that proof will they accept that you are putting all your salary for gambling, will this violate the principle of gamble for fun, because you are working to gamble based on your proof income.
Not just casinos, but I have also seen many exchanges require absurd documents in order to release players' money.
Strangely, they only ask for these documents when the player tries to withdraw, why?
If the casino suspects you're spending more money than you should, they should block deposits, not withdrawals, agree with me?
Blocking withdrawals always causes a bad impression, most online casinos that have an excellent reputation take great care with this, as no player tolerates an abusive practice of withholding player money under the pretense that they are just complying with KYC.
In any case, every casino has its own laws and way of validating the documents sent to it.
If the blocked amount is really important to you, send all the documents they ask you to do, as you will not have an easier alternative, unfortunately.