How do you judge Musk's million-person threshold for a self-sustaining Mars city?

Editorial context

Editorial context: one million is Musk's planning estimate, not a measured minimum population. Here, self-sustaining means able to keep functioning without essential supplies from Earth, not merely a continuously inhabited outpost. Skills, automation, local food and energy, replacement parts and health care would affect the population needed. The source does not demonstrate that a million people would be sufficient. Judge whether his population estimate is too high, about right or too low; you may instead reject the feasibility of self-sufficiency at any size or say the evidence is insufficient. Results reflect reader opinion, not a scientific finding.