It's just another phenomenon that gamblers often assumes that they have some control over the outcome of their bets especially if they have been doing it for a while even though every time is just purely random there's no skill involved. Take dice for an example we might assume that we can control and influence the result of it by throwing softer or harder or in anyway that our brain recognize a pattern and keep tells us it's a way to win the game.
There is no need for a soothsayer before people know that such a person is deceiving himself and no wonder they fail bitterly in gambling. I don't know the aspect of the casino games you can master and be earning consistently with for a long period. Has that not hinted to the person how careless it is to think a pattern or control has been discovered? I advise anyone gambling casino games to neutralise his mind on the outcome, particularly, on the money because no one can ever guarantee a means of doing it better than luck.
You probably forgot that there is poker, where your skills, experience, knowledge of mathematics play a decisive role. Of course, there is no 100% guarantee that there will be income every month, but I have seen many players who rose from the very bottom, for example, from the HK2 limit.
You have a point, and I tell you, I considered it as well and even more because poker games need skills too and I've said it on this forum that I know of lottery games that people win with calculations. They use the past results of the game to analyse what will happen and they win. But if we average everything, we can't still say casino games are skill-based for profits to be made, we need more luck. If it was as simple for people to make money with skills even in poker games, many would have been the professors of the game and punished the house for their money.