Let's first ensure we do all possible things as a species and a collection of communities to restabilise Earth and give ourselves a 99.5% chance of healthful survival for the next 200 years, which is probably the reasonable timeline until we can establish more or less independent non-Earth habitats that can survive without Earth indefinitely. This is like expressing the wish of wanting to run while simultaneously ign…
Why not do both?
As long as it will be the case, we won't be able to start new, large scale projects without jeopardizing our ability to live on earth.