[ChuckMcM]

There is one school of thought that goes that SpaceX's mission to "Get people to Mars" requires so much more than simply putting things in orbit that people set their expectations that this is only the beginning. If you set your expectations that you just wanted to get to space and straight back down again, you don't invest in things which would be helpful to a Mars mission.

So while building a resuable booster for rockets might be the entire goal of some company, for SpaceX it was only the first step in a lot of bigger goals in order to make it feasible to go to Mars. And in so doing, and creating a capability that they can sell today to fund future development.