A friend of mine is a big advocate of space habitats. Apparently they are far superior to Mars as a place where we could expand in foreseeable future. Maybe someone knowledgeable could chime in?
As a destination Mars is less hospitable than say the top of Mt Everest. And far harder to get to. For an easier visualization, imagine an orbiting space habitat vs a Mt Everest peak habitat.
Interesting...did he work at NASA working with real space habitats? I was a summer hire at NASA many moons ago in the medical/habitat programs and there sure wasn't much their that looked superior to anything.
I propose saving this planet, and not messing up another one.
If not many, then how are we going to choose who to shove there?
What if it will turn out discriminatory?
And if they are discriminatory, you gather an asteroid and build another one. More than 99% of the difficulty is gone just by the fact that you are not on a planet's surface.
We are, of course, far from being able to build such things.
One can perhaps start a commune in a forest or on an island even today, with handpicked people, but it doesn't happen.
Wanting to flee from Earth with all its problems is understandable, but I fear that we'll repeat a lot of bad stuff in habitats. Think totalitarian cults, slavery, plain old totalitarism.
No idea how we may get people there, neither socially of physically, but this is what is possible. I'm also in no rush to get there, but we will someday, because it is just too tempting. (More because of energy availability than any of the above paragraph.)
But for the others, with just a reasonably low delta-v and some patience you can get into cubic kilometers of unclaimed raw resources for extending your habitat. You just have to know how to use them (what we currently don't).
You'll certainly get a bigger density of material resources on any planet, but then you will be trapped inside a gravitational wheel and must spend all that delta-v again to break free from it once it's completely claimed. For the short term (to the point that any timeframe is "short" in this discussion) small moons and big asteroids are probably the best places to colonize.