It seems you read the wrong definition of gambling somewhere on the web. I’m not sure why someone will consider gambling as source of money while casino house edge on all of their games meaning you have higher chance of losing against casino in the long run so how can you make money.
Yes, if you get lucky you can earn money but there’s no assurance that you will keep winning especially that your goal is to make money.
You will read lots of this same testimony as yours from gambling addiction interviews because that’s how they started to become an addict.
Correct, the very definition of gambling at least for me is putting a bet on the unknown, like in sports betting. And with that, there are a big chances that you will not win so it's hard to consider gambling as source of money. And even those pro in the poker tournament, it's not a guarantee that they will win and bring home some money.
So don't think that it will like a job or something because it will really be tough for you if you consider gambling that way.
And we can enjoy even if we lose some money. We have seen threads discussing about it so maybe it could still be a source of fun and enjoyment for some.