Even then - if the Earth were completely taken over by autocrats, it would still be easier to construct and defend an impenetrable fort on Earth than it would be to construct one on Mars - else the autocrats controlling the Earth would easily conquer (or destroy) Mars as well.

Now, if we were to think of a colony ship or a colony on a distant planet light years away, that would make some sense, but that is probably a project for the year 5000, not 2000.