I don't see what baffles you. 1. Predicting that humanity will be able to geoengineer Mars in the future says nothing about our current abilities 2. A single

I don't see what baffles you. 1. Predicting that humanity will be able to geoengineer Mars in the future says nothing about our current abilities 2. A single person/company/government deciding to geoengineer Earth is obviously incredibly controversial, as siblings already pointed out 3. Mars habitat wouldn't be free and Phoenix doesn't have the budget to cover the entire city in some kind of domes 4. People who settle Mars choose what they are getting into. I doubt that all Phoenicians would want to live indoor even if someone rebuilt their city into a space colony for free