I'm more pessimistic about the politics than the tech. While there's huge issues going from e.g. current nuclear arsenal to a working Orion drive, that's at least plausible; the idea humans can be in a tin can for a century without ending up with enough people who think "'the outside is a deadly vacuum' is just a conspiracy" for one of them to cut a hole in the wall, is where I think there's no line of sight to a real solution.

We had a pandemic for just a few years and people were treating boring minimal PPE used by every dentist and surgeon for decades as some secret ploy for control.

We, as a species, are not yet ready for large-scale life off Earth; not even within our own system.