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.
They ask your proof of income you provide and if it did not exceed your bankroll then you are good to go, there are still ways where you can get money to play not only coming from your income, like a sale of property from the inheritance you are not violating the principle of a gamble for fun when you only spend that amount of money it's not even $5000, you are still good to go unless they ask for more proof and you cannot provide anymore except your income.