Do you read the TOS of a gambling site? Honest answer please.
Done.
unfortunately not all gambling sites can provide bonuses for new users because if the gambling place provides that method many will register and try to make withdrawals to their wallets, maybe if they give a bonus there must be a minimum limit for making withdrawals which might be used as a solution best for gambling places.
I do not know any gambling site where you can withdraw the bonus immediately after receiving it. Usually the site requires a certain number of games, make a certain number of bets and so on. Such rules are provided so that people do not register multiple accounts and do not withdraw bonuses from each of them.