Even if a meteor the size of Texas hits us, Earth would still be a more pleasant environment than Mars could ever be.
Besides that, instead of financing a colonization of Mars, they could as well finance a mission to destroy the meteor or change its course.
Yes but what if we suffer one last gasp of flood basalt volcanism? You wouldn't be able to breathe here either.
It is always good to have as many worlds populated as possible. Even Mars may not be far enough. We have DM 61+ 366(HIP 9481) Gilese 710 coming in:
According to the Starflight Handbook, DM 61 366 is supposed to come within .29 ly of us, with a one light year margin of error either side. That could mean a clean miss--or a When Worlds Collide scenario.
Moreover, we have WR-104 perhaps aimed at the whole solar system: