Earlier quoted context omitted.
The colonization of Earth was accomplished with brute force, not visas.
Imagine deep sea exploration. Someone finds something very valuable and worth extracting despite the cost. There are treaties for this, of course. But would it work the same for Mars? Or, would we revert to force, as you say, if the Mars colony declares independence and says, no more Earthlings or only Earthlings from Country X who pay us handsomely.
It worked out fine for the USA.