Good points - which is why I suggested working on setting things up BEFORE sending people there, to avoid a Mark Watney situation. (A backup ascent vehicle would be nice.)
And yeah, we will likely see a permanent Moon base a lot sooner than a Mars settlement (hopefully within the next decade thanks to the Artemis program), and this post is speculative at best.
And yes, these things WILL take astronomical (heh) amounts of resources, at least at first. And for a while at least, the only people going there - and back - will be professional astronauts.
However, I think it's possible. Probably not with current technology, but within less than a century of sufficient research and development it's hard to tell.