How is it a business if not for money?
Money is part of how you get there, but it is not a goal in itself. Many start businesses where money is the main goal, and where the amount that you are satisfied with inevitably shifts once you get richer
They also have a paid API.
"Side" in the sense that my main income coming from somewhere else, aka my "normal" job
Money that doesn’t need to be spent is freedom of time.