Elon mentioned that just 1% or less would be needed to help make this MAR mission possible and productive.
I guarantee you that if we had hard scientific evidence that Earth was going to be destroyed by the largest Meteor or Astroid that has ever been known and that it would happen in 10 years, you'd see a heck of a lot more than 1% be possible!!
People are very complacent, without urgency until the end is near, then that practically panic and run over top of each other to find a solution!! Is that type of mindset in a civilization really worth saving?
What if the Earth and all its inhabitants were totally destroyed with no possible survivors (no space station occupants, etc.). Would it really matter in the grand scheme of things? Probably not! We humans like to revel and bask in the glory of our creations! Much like a fictional GOD would of his children, people, creations...
It's hard to think about not existing at all yet one day each of us will take that final breath. Then it's lights out, stop thinking, stop dreaming...just stop! Nothing.
Mar will likely never be like life is here on Earth so to all those future kids, take a good look and enjoy what time you have on this Earth. Nothing lasts forever...