Then all you are doing is expressing concern for the survival of humanity on a racial or species level - the most abstract level possible. It would be much better to do what we can to develop forewarning for people living NOW, and also encourage revision of practices in building structures and locating settlements. That might sound like a tall order but it's actually a lot easier, ie within our technical capacities, than going to other planets, far less terraforming them. We have only gone to the moon, and even that was extremely risky.

So, that argument is silly and irritating for 2 reasons:

(1) We can be caring about people alive now and in the near future instead of some abstract pipedream which, face it, is NOT anywhere within present capacities.

(2) The reason to go into space is to EXPLORE and to do science, and that is MORE THAN ENOUGH good reason for space travel. Why load the argument with facile abstract arguments for the survival of the species? We already have the capacities to improve the survival of humanity right here and now. Using that to argue for space travel is a bit like always pointing to the technical spinoffs from space research: people who argue that way are just too embarrassed to point to the real and proper words: "SPACE EXPLORATION"