No light for part of the year vs no air ever. Hmm, let me think about that one for a minute.

I think settling Mars will and should happen, but anyone who doesn’t realise it will be thousands of times more expensive, risky and dependent on external support than eg Antarctica I think isn’t really grasping the difference in scale of the problem.

Yea, I mean, just as far as accessibility, it costs 10,000 times more to deliver a pound of cargo to the ISS vs McMurdo station in antartica. I don't have numbers for the building and maintenance of the two stations, but presumably its even more than that.

Mars does have an atmosphere, although unbreathable.

I don't think it's called air if you can't breath it.