I made a topic related to this in the gambling discussion board a couple of days ago - https://bitcointalk.org/index.php?topic=5242329.msg54268710#msg54268710

While, you are right to an extent, winning in gambling is still very much possible. The casinos and gambling platforms have a predetermined edge over the players and this would eventually be evident if one plays for a long time. But in a couple of games it's very possible to win and make profits.
Also gambling platforms are charged to maintain fairness, so the players are not entirely at a loss.