I'm not sure how the existence of subscribers and profit negates the point. Their are plenty of things that have those that aren't useful beyond a capitalistic sense.
SpaceX provides internet access. Millions of customers pay for it. The revenue from the customers is more than enough to cover the business costs. The negative externalities are much smaller than say... aircraft or cargo shipping. If a sustainable business like that isn't enough to justify usefulness, then what is?
