That’s literally moving the entire population of the planet — you’d only do that in a very unusual circumstance when most people were going to die anyway if you didn’t leave, and building domes over your cities does nothing to help.

Most people don’t even move more than, what, a hundred miles from where they’re born? Just because I fancy giving it a go doesn’t mean I expect people to go to Mars en masse even if it was free.

But they could if they needed to.