Disagree, you get to space using fossils and then what? Can't ship everything from Earth, the surplus is not that big, you need local industry first. I suspect even hundreds of starships won't be enough, our technology is incredibly interdependent. Only then you can build self-sustaining ecology.

Industry needs loads of energy and only practical power sources in space are solar (up to some distance but there water is scarce) and nuclear.

So if there was a missing chance, I'd say it was developing ubiquitous nuclear power. Would help on Earth, would help in space.