“Actually (assuming Mars does still have some ice left), a pretty significant number of humans live worse, now. “
No true. Winter temps at Mars’ poles is about -229 f. And the polar ice? Its mostly carbon dioxide, not water. The poorest human do not live at those temps and even if they are “cold” do not have frozen CO2 versus frozen water. And none of that changes the fact that they still can’t live openly on the surface. Sorry. The poor will remain poor and not “immigrate” to those Martian conditions.
I’m talking about living underground. You seem to think that’s impossible. Ever been to the large venues in Vegas with simulated sky, etc?