The psychological problems of people attempting to live on Mars would be huge. In addition to the “stuck in a tin can” problem we can add the necessity to live in concrete underground bunkers (to avoid all that solar radiation that Mars doesn’t block because it has no meaningful magnetic field) and the terrible long-term effects of 1/3rd gravity on human physiology. So we’d basically be condemning people to lifelong suffering, in return for … what, exactly? People have for too long gawped at Star Trek etc. and failed to understand the reality that humans are adapted for life here on Earth and nowhere else. Furthermore, there’s zero value in sending people elsewhere because robotic missions can always do more, more cheaply. It’s time we grew up and stopped imagining real life is like a children’s cartoon. We should continue to explore and learn and discover, but do so in the very best way possible: via robotic and automated missions.