The huge bet was used on buying bonus feature which OP is known for doing it since it’s the main source of his winning. He realized that he can’t withdraw all his profit at one go so he make an excuse to accuse the casino that his account was hacked while leaving his account security very vulnerable to have a reason for an excuse.

Being impatient is very common on gambler so I definitely don’t believe that someone hack OP account because you will not leave your with weak password and security assuming you have huge balance in there.