Honestly, I find it quite strange to see why so many gamblers find it difficult to ignore their greed, especially when they win, but the reason is certainly as we have guessed that they most likely gamble without any understanding of what and how gambling really is, I am sure they are involved based on misunderstandings so that they always have unrealistic hopes and beliefs in an activity that runs based on probability, and the impact we can see that it really happens and is experienced by gamblers who are now trapped in a cycle of addiction.
You're correct, but we can also not ignore the fact that when someone wins, there is this happiness in them that arose from the feeling of overconfidence that they can win more. Just like if they can win that amount, what then stops them from winning a higher one?
Another thing again is that now there are available funds after winning that can be used to level up their gambling experience, which only the strong can resist that feeling.
On the other hand, as you have learned, gambling is not a place we can rely on to earn income, and the reason is clear because no matter what activities that depend on probability can never be made a hope.
This is very correct, and the more you try to make it your source of income, the more you will spend the little you are managing to make from other sources of income until you have nothing left. It's better we just treat gambling as it should be and keep the high hope of winning big or regularly aside; if the winnings come, we consider it a bonus.