Colonies
Two or three hundred years ago I'm sure any reasonable person standing where Las Vegas is now would not have seen that coming. The city of Honolulu was shipped there, bit by bit, in boats.
The only reason humans don't live underwater is lack of air. Primitive free divers go deeper into the ocean than any other animal on Earth not specifically evolved for it.
The only reason people don't live on the polar caps is the lack of food. Go south from the North Pole and the minute you hit land and any open water at all, you hit people.
If somebody finds a good enough reason to live out in space, they will.
