The same way that free mobile games make most of their money from 1‰ of the 'whales'.
Nom mobile games. Let's say team fortress 2 or other games subsidized to make game free for all. When a small portion are buying crates and skins.
Uber could do same with black car. Delivery services. Etc.. And then offer discount /free for the (multiple independent ride share or other) to those that want to be cheaper.