There is no “unsupportable assumption in the first sentence,” so you can go bury your head in the ground like a Know Nothing and we will proceed to ignore your baseless objections.
Of course there is. You’re not a fortune teller, so you have no idea what the ultimate fate of the human race will be, with or without colonizing other planets. You assume that we must colonize other planets or face doom, because you require that assumption to make the rest of your arguments.
I’m not against space exploration, by the way, but am saying that more solutions are possible. But technical minds should also be enlisted and tolerated by the impatient, sensitive class—a tolerance that’s somewhat rare now.
In my opinion, every extensively educated engineer, manager and investor should watch “Tucker and Dale Vs. Evil.” It’s a movie fiction, but there’s much truth in it. It’s also very funny and entertaining. [I once lived in the Ozarks.] In equipment development, more experiences and associated perspectives from more realistically grounded people (sans much from the liberal arts or academic social concerns) are needed along with much more distributed efforts.