If every time I drove my car it was spent and I had to use a new one every day it would get pretty damn expensive. If ever time I used my computer and it was spent and I had to get a new one it would get pretty damn expensive. If every time a trucker hauled a load and then needed a new truck for the next load it would get expensive. If every time a ship made a transatlantic or transpacific trip and then needed to be replaced it would get pretty damn expensive. Well, the space industry on this planet has been doing just that for the past half century.
Space X just moved us closer to expanding the human race into space by launching a rocket into orbit and landing it for the second time.
Being able to reuse a rocket multiple times will reduce costs and make space industry a viable pursuit.