Someone can win the casino but it's very rare, you need to be extremely lucky to do so, it happens once in a while and that is why most gamblers wants it to be them. If you're gambling with small amounts then one day you became lucky to win like 1000 times more than the total amount that you have spent on gambling I will say that you have won the casino. Also a new gambler can have beginners luck and win huge amount of money on their first or second gamble, the gambler has also won the casino. But the problem is that in most cases as long as the gambler continues to gamble they'll most likely lose everything or almost everything back to the casino.