Before this question can be considered in realistic terms, the answers to two other questions need be forthcoming; Can people get to Mars alive, and once there, can they withstand the harsh environmental conditions they will be subject to? One thing is for sure, Mars can and will never be as hospitable as Earth. So who would want to live there?
Probably the closest thing we have to Mars climate would be Antarctica, but even there the air is oxygenated and atmospheric pressure is standard. The Atmospheric pressure on Mars would be equivalent to living atop Mount Everest. Since most plant growth occurs at temperatures well above freezing, it is not likely that you could grow anything on the Martian surface, even if the soil conditions were optimum. Therefore, resupply from Earth would be a continuous necessity to support a colony on Mars. Again, who might want to live there and depend on the continuity of Earthly support?
One thing Earth has, and Mars doesn’t, is a magnetosphere. Just exactly how important the Earth’s Magnetic field is to supporting life on this planet is not yet well understood, in large part because with the exception of a few very brief trips to the Moon, no living organism has ventured far enough and long enough away from earth to find out what the effects would be.
Just a first excursion to Mars will be fraught with such enormous complications, perhaps the most complex feat ever attempted by the human species, that the probability of success can not be certain, and the mortal risk for those who make the trip is substantial. The peril of a return trip to Earth is a prospect no less daunting. We’ve sent quite a few space craft to Mars and the other planets, but we have yet to land one of them on an extraterrestrial body beyond the Moon and then return it safely to Earth. Keep in mind, the Earth is a moving target traveling at 66,000 miles per hour, and close just doesn’t cut it when you have a one shot trajectory to get back here from Mars. If any man or women does ever set foot on the ref planet, they will do so knowing that the odds of them making a safe escape from Mars and returning successfully to Earth are less than 50/50 in their favor. This is, of course, assuming we can invent the technology to make a round trip to Mars possible in the first place.
It would seem that a prudent mission plan for a trip to Mars would have a contingency for people once on Mars to stay there indefinitely or at least until a rescue mission could be attempted. There was no such plan for the Astronauts who visited the Moon. If anything went wrong, well….. The point is, if somebody could get to Mars, who on Earth is going to be able to tell them they can’t stay there? Once they land on Mars they become a nation of Martians unto themselves and it might seem more logical to wonder whether they might prohibit other Earthlings from coming to their new home. You know, kind of like the situation between European countries, and their colonies in the Americas a couple of hundred years ago.
Let’s face it, if any humans do make the trip to Mars, fall in love with the inhospitable conditions there and decide to make the move on a permanent basis, there isn’t a dam thing anyone back on Earth is going to be able to do about it. Given this bit of logic, it would seem a moot point. People should and will be allowed to live on Mars, but I’ll bet ever penny earned by this article that nobody alive today is going to have to worry about it. Each an every American is already in debt to the tune of 30,000 dollars and it doesn’t look like there will be any money for a Mars trip in the foreseeable future.