Being able to leave your home planet in a functional, safe & unimaginably fast aircraft is one thing, but pockets of civilizations surviving on other planets is another. No one has a clue how terraforming a planet would look like on a much more developed level, but it’s plausible it’s basically impossible to do without waiting thousands of years for your compatible life to establish a proper ecological cycle.

Basically no one has proven yet that it’s possible to build a small self sustaining habitat on any planet. Elon talks about going to Mars, or used to anyway, but this is an important problem. Can you imagine humans for real building a megastructure on Mars that can sustain a settlement? It feels way too problematic tbh, even if you had 10% of the World’s GDP to give it a good go.