No, the stock market is not gambling (or at least hasn't been, need not, and should not be). The stock market is a positive sum game, linked to the growth of the economy as a whole. Humanity is very, very far from the maximum possible utilization (and maximum efficiency) of matter and energy in this solar system or even this world. What decisions we make matters a lot in how well/how fast/whether we continue to get richer, so we've tried however ineptly and haltingly to make systems that reward short and long term gains balanced against current use priorities. And have failed plenty, and may yet fail completely. But it's perfectly possible for everyone to win, for the whole world to get "richer" (defined as being better able to meet human goals & desires within a given mass/energy budget or have more or both). Investments can yield >1x total returns. And that has indeed been the case, that's the story of modern civilization.

Gambling in contrast is strictly zero sum at best and always negative sum in reality. A group of people puts in 1x capital, the house takes a cut of that, and then the <1x gets unevenly redistributed and that's it. Nothing is generated, the collective set of people is strictly worse off after the gamble, with a few making gains off the backs of loss distributed amongst everyone else. All while hacking dopamine reward centers that didn't evolve for that.

It appears to be the case that we can't perfectly stop 100% of all IRL gambling without a cost that exceeds the benefit. That's life. But that doesn't mean we shouldn't be picking as much low hanging fruit as possible, same as with other negative sum brain hacks.

The problem with this comparison is that it only really serves to water down the very real harms of actual gambling.

Unlike sports gambling or casinos, the stock market actually does have some legitimate utility, as compared to being (at best) pure entertainment.