I agree that they are a zero sum game, but I’d argue that the sum is a net positive for traders over a long period of time, and the people who are systematically loosing are the workers who’s true earnings were siphoned away from them and onto the stock market, where they are sold as derivatives.

This manifests in e.g. how much cheaper it is for people to borrow money who hold a large stock portofolio, how interests in a normal savings account are usually much less than people who keep stocks, etc.

If you trade in derivatives perhaps every individual trade is a zero sum game, but taken together a whole year of trading yields benefits regardless, and that is also a zero sum game, but this time an unfair one, where you are guaranteed earnings at the cost of the workers.