The stock market was so gambling that we had 'bucket shops' where people would just buy and sell fake stocks that tracked real stock prices.
Now we have public companies directly selling shares with no voting rights and no plans to ever pay dividends, which is the same thing.
No, that is not a strict definition of gambling, that is your own loose, personal and casual definition. The strict definition of the gambling in question under Arizona law (the subject of this article) is I believe partly under 13-3301 [0] and has a number of criteria that clearly differentiate it from investment (whether it be stock, loan by a bank or any other entity/person, or whatever else). Other polities will have their own flavors, but all of them are aimed at a net negative, destructive social activity. That's the whole point of regulating it, it's not some metaphysical philosophy thing about life having uncertainty it's about long experienced concrete harm. Trying to argue that buying shares in a broad index fund is a "wager that a meteor will not hit the Earth" is uninteresting.
>Just because it (often) is positive sum doesn't mean it isn't an unknown that people are betting money on.
It does actually! Positive sum changes everything in terms of collective incentives, strategies available and how investors can hedge risk. You may not choose to make use of all the tools available, but that doesn't make investment the equivalent of gambling. Part of the whole point of markets is to manage changing risk and information discovery (including dead ends) such that we still continue to grow overall.
----