[evgen]

If you are operating over a large and crowded area you are going to be facing more competition for customers (from competitors that can use the population density to justify the initial build costs of better infra) and you are also going to be facing more spectrum competition and interference. While flying over the corn fields of Iowa may not seem too useful, each plane could have a relatively large footprint and could also be used to enable a lot of non-urban IoT applications. Sell bulk bandwidth to precision farming equipment shops, mobile applications in the area, and households poorly served by old copper telco infra. Not necessarily huge bucks, but you could probably do it at a cost that would crush competing data providers in that plane's footprint and lock up a nice little revenue stream.