It is not possible for any modern technological society to be "perpetually self reliant" with a population of less than a few hundred million people. And that's with access to a planet's worth of resources. Hell, it wasn't even possible to have a bronze-age civilization without international trade. One of the reasons the transition to iron/steel based civilizations was so widespread was that there's a lot of iron ore and it's spread out all over the place.
It turns out that resources are not evenly distributed. There are only a handful of locations where it is economically feasible to gather or mine some elements. And until we have techno-magic replicators that can turn energy into matter, this problem will remain.
No colony 100's of thousands of people is going to be self-sustaining on Mars. It's simply not possible. They will always be dependent on Earth.
It turns out that resources are not evenly distributed. There are only a handful of locations where it is economically feasible to gather or mine some elements. And until we have techno-magic replicators that can turn energy into matter, this problem will remain.
No colony 100's of thousands of people is going to be self-sustaining on Mars. It's simply not possible. They will always be dependent on Earth.