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Some people can win a huge amount as jackpota but yet the amount that they won can not be compared to how much money they have lost in entire life while gambling, can you say such person has won the casino because they won a jackpot?
If you believe that sometimes, gamblers can also win the casino, kindly drop all the explanation of why you have such a believe.
It depends on the previous amounts of money which the person has lost to the casino and whether that jackpot overcomes all those losses which have been accumulating through years, though.
Also, one does not need to exaggerated amounts of money for one to say one has defeated the casino.
I have a friend in Chile who was invited to gamble in one of the most luxurious and well-accomodated casinos in the city. He had never gambles before, so that casino had never take money from him.
He decided to play blackjack and by the end of his session he had been lucky enough to pocket 50 dollars from the casino, instead of getting greedy and continue to gamble, he called it a day and quit the casino with that money. In those specific cases a person can defeat the casino and take money from it, as my friend did not intended to gamble again, as he does not consider himself a gambler, he just didn't because he was invited by some friends.
So it is possible, in my humble opinion.