Sample argument against:

As far as I can tell there is zero serious basis for going to other planets in order to save humanity and it's an idea which stays alive merely because of science fiction fantasies and publicity statements from Elon Musk and the like. I've yet to see a likely catastrophic scenario where having a human space colony would be useful that would not be much more easily protected against with infrastructure on Earth.

-Can it help prevent x-risk events? Nope, there's nothing it can do for us except tourism and moon rocks.

...

I really fail to see the logic behind "Earth might become slightly less habitable in the future, so we need to go to an extremely isolated, totally barren wasteland that is absolutely inhospitable to all carbon-based life in order to survive." Whatever happens to Earth, it's still not going to have 200 degree temperature swings, a totally sterile geology, cancerous space radiation, unhealthy minimal gravity and a multibillion dollar week-long commute.

Sample argument in favor:

All I know is, the best way to make sure your servers don't go down is redundancy. You can do a lot of things to make a single server more reliable, and you can even convince yourself it's essentially bulletproof, but you'll probably be wrong, and a risk you didn't anticipate will ruin your clever plan.

Obviously there are disanalogies (e.g. a redundant server can be just as good, but the OP is mostly about why the moon is a much crappier server than Earth). But I think the core point that black swan risks exist, and redundancy is the best way to protect against them, is relevant.