Usually large gambling sites that have a good reputation will not refuse payments without giving a good reason. For example, gambling users cheat when gambling and get big wins. and that's when the site will refuse payments that have been received by users.
like several times I read threads there are gamblers who complain about playing on gambling sites that have a good reputation getting big wins but the gambling side refuses to make payments because the gambler cheated while playing

there is no need to look for legal means just to make sure that the platform will pay off. as long as you play in gambling without cheating and don't make other mistakes that violate the rules, of course the gambling platform will always pay out that big win