> how difficult and fraught it is to keep a few people alive down there, how does anyone expect to keep a few people alive on Mars, let alone build a colony there?

Necessity is the mother of invention. It makes no sense to use precious Antarctic time and space growing all the food when it's cheaper to ship it in. Similar to how civilizations with a history of littoral shipbuilding figured out ocean-faring--if you're always a day from port, you don't bother baking hard tack. That doesn't mean you can't.