SpaceX itself replicated the DC-X from the 90's. The reason the DC-X was cancelled was because of the economics. Reusable rockets are a solved problem, with only the economics of it a barrier (see Space Shuttle). SpaceX has to rely on their own investor funding for Starlink to remain a viable entity.
The DC-X was stupid, dumb, insane, bunkers, and a waste of money and not replicable.
"sure, let's put four RL-10 hydrogen engines on it! They are expensive and the worst possible for the low-altitude flights we are going to do so some sucker will believe we can do multi-stage reusable flights to orbit".
"sure, we don't actually need to go to orbit anyway. That was always a dumb idea. Who said we ever wanted to do that? No, suborbital is really useful, we promise. And we are going to do it with a single stage (using hydrogen) cuz we are so smart and the future and everything!"
"sure, let's build a specialized hydrogen tank in a stupid shape."
"sure, let's give the whole single-stage low-altitude rocket a k00l shape that makes it more expensive."
"People knowing it can't be done shouldn't interrupt people doing it wrong."
