Monopolies are efficient, that's why they exist and survive. The bad part is that they can capture all the economic profit from an activity. But there doesn't necessarily matter for leisure activities like space travel.
Monopolies are efficient given status quo processes / technologies / business models, but cause development in all those above areas to stagnate. Ergo monopolies create inefficiencies given the march of time. It's bizarre that I have to state such a thing on something like hacker news.