Waaah trying to fix the environment is too hard.
It's easier to simply create a new home on a world without air, water, food or energy millions of miles away.
I know if human civilisation survives more than a million years here on earth then yeah eventually we'll have to leave, but leaving now??? So shitty.
Mars/Moon/Culture Orbitals are fun and cool, but they're not solutions, they're hobbies. It's shit we do for fun while building Socialism, which will have the eventual nice side effect, several centuries down the line, of reducing our resource footprint on this planet to near zero.
It's not going to bail us out of our problems, Space Solar power and mirrors might help and having some infrastructure, even some asteroid mining, is a good idea, but it's no substitute for the hard work we need to do here.