I think we have the technology now (or in the next 100 years) to move some of our people into moon bases here on earth.
If I were Musk I would be building these now.
If I were Musk I would be building these now.
Even a completely 'trashed' earth that renders billions displaced or suffering amidst ecological catastrophe is still infinitely more hospitable to life than celestial bodies that are completely devoid of that benefit in the first place.
https://www.youtube.com/watch?v=g1Sq1Nr58hM
But more pragmatically, neither Biosphere project was considered successful enough to make this workable on earth at any large, or even small, scale. There is still much more work and research to do here. Any attempt here currently has a hard dependency on the larger ecosystem to supply it with inputs.
Musk working on building moonbases on earth looks a lot like what doomday preppers are already focused on.