I am someone who has always had the understanding that no one can live as a gambler, regardless of whether he is rich or not. Gambling cannot be used as a source of income, you can imagine how a person can live by gambling while he has to spend every day to live while he does not ensure that every time he gambles he gets money, psychologically this is something that can be accepted.
You've got a point .. basically, when someone is gambling they are taking risks for uncertain results in the hope of making a profit. So making gambling a source of livelihood is something that doesn't make sense because they have to depend on something uncertain.
But strangely there are people who take this path which in the end they will be faced with losses and after all the house always has an advantage because the odds are created to the house's benefit.
While this might be the case for many of us, there is definitely a group of people who like risk and uncertainty. If you don't look for it you go for a safe 9 to 5 job without any upside. Your salary is fixed and you won't make any big pay jumps. People in the finance industry work a lot based on bonuses, so their salary is uncertain too. Or people working in sales are paid by commissions. There is also a change your salary per month.