I do submit that a person may consider that they have "won the casino" if they can fully stop going to it. This simple answer hides lots of implications and meaning given the current state of gambling among individuals who see it primarily as income.
To explain further the statement above, a person may have "won" the casino if they have stopped gambling at all. This kind of approach even goes beyond the scope of earning income because in gambling, profit is not just the goal of the players but also to its complete stoppage.
If you believe that sometimes, gamblers can also win the casino, kindly drop all the explanation of why you have such a believe.
The only time I think someone can win against the casino is when they newly just got into gambling or they’ve been gambling for a while but don’t gamble with a lot of money so haven’t lost much to the casino and as you said in your post they luckily won a jackpot which gives them back all they have lost plus a very large profits and instantly quit gambling - that’s one way I think a gambler can win against the casino.
But if they continue to gamble, it will get to a time when their losses will cover all their profits and before you know what’s happening they’ll fall back to the losing category.
While I do also think that it is a case-to-case basis on what is the definition of "winning over the casino," I do think that it even encompasses hitting the jackpot. To give a metaphor, a student can considered "winning over the school" if he graduates from that institution. Even if he receives academic honors in the process, without graduation, he fully cannot say that he won over that school.
Same application with gambling- once a person has decided that they will quit gambling and pursue a different path, then you may consider that they have "won" over that casino.