What is "a lot of money"? SpaceX is a private company so we have no way of comparing their launch costs to other companies. Why aren't other rocket companies switching to landing boosters? Why hasn't Blue Origin made more progress following a similar route? You're right, fuel is cheap-- until the time it's put into a rocket. Then it becomes VERY expensive because every ounce of payload requires X amount of fuel.

Landing those boasters if a modern marvel. Don't get me wrong. I'm glad I lived to see the day. However, physics are physics and economics are economics. Innovation is crucial. Dreaming is crucial. But so is pragmatism and clear-eyed analysis.

If you have deeper economics of it I'd love to see it! Thanks for the comment!