Anything where you're putting money in and hoping to get more money out, where it's a zero sum game and any winnings will come from other people doing the same, is gambling imo. A gamble can be a good financial investment if you only do it in situations where you know you have some kind of edge, but doing it for fun is stupid because it fucks with your emotions and you're just going to get screwed out of your money that way. If you are playing against people gambling for fun, rather than playing against "the house", that might be one you can win.

Morally I think the ideal situation for gambling is one where people in bad financial situations get together so at least some of them can escape those situations. The worst is when people who don't need more money ensure all of the profits will go exclusively to them, and no one else will really win.