A long time ago, I read a book, "This Place Has No Atmosphere". I don't remember much about the book, except the cover, which depicted a glass bubble with a person sitting inside. On Mars, you'd literally be living in a glass bubble, and be dependent on the whim of people from Earth. Sure, they'd eventually get some sustainable life, but you'd have to live in fear of a meteor breaking the bubble--or an earthquake, or human stupidity, or weakness from the Sun, or just about anything.
Hmmm. The first colonists...