Here's a fun question: how much of what Starship is doing would have been impossible in the 70s?
In my view, the reason we don't have space colonies already is because we decided not to. Nothing we're doing now was strictly impossible then, just a little bit harder. No one was trying, was the problem.
It reminds me a bit of Brian May. In the early 70s he was getting a PhD in astrophysics, studying interplanetary dust. He stopped because his band, Queen, was doing pretty well. In 2006, he realized no one else had ever picked up his particular avenue of research. He resumed his PhD research and completed it.