I'm not saying that everyone trading has idealistic, altruistic reasons for doing so, but products are built on the back of capital markets.
At least ideally, successful trading makes markets more efficient, and making markets more efficient ripples out making it easier for many people to make many products that create value for their users.
Even if all of that is true though, it's an unnatural framing for people to work with and is much harder to find existential meaning in abstract changes to the system that make people's lives better in complex and hard to trace ways than it is to find meaning in a direct value proposition to your users.
At least ideally, successful trading makes markets more efficient, and making markets more efficient ripples out making it easier for many people to make many products that create value for their users.
Even if all of that is true though, it's an unnatural framing for people to work with and is much harder to find existential meaning in abstract changes to the system that make people's lives better in complex and hard to trace ways than it is to find meaning in a direct value proposition to your users.