If a gambler chooses the right game, he can definitely make a profit and most importantly he always learns from experience.
and from what I have explained, does it prove that today you already know people who generate sources of income from gambling?
Right game is not enough, the right startegy is important as well as that will give you the win, a consistent win that we are all wanting for. One shot or big shot win could make us make big money but we will still come back to gamble, and that will eventually result to losing what we won, so it's not working, we need some kind of consistency to gain that profit.
Even if you make everything right as you think that would give you chances of a consistent win then I think it would be impossible as we know that gambling literally relies upon luck. Unless you are a real genius where you can make your own formula to calculate the probability that you would win like Pascal. Plus you cannot say that a specific game in the casino is the right game for you, so in the process, you would try where it fits you but you could still lose a lot of money. Your skills and strategies would go straight to waste if you are not lucky in a game. Imagine you exert effort in determining how to win in many possible ways but the other player won by just simply betting randomly.