Comment by Kim_Bruning

This argument is plausible for short range so long as there's no mass produced spacecraft with a payload capacity of 100 tons and with a range to reach Mars (at a launch cost expressed in millions, not billions). I'm cautiously optimistic we'll have that capability in the next decade or so.

At the same time we don't have the ability to reach other solar systems at all, nor projected in the next few decades. So we know relatively little about them in fact. Only as much as can be obtained by remote sensing over light years. (Which is to say: not very much.)