Nobody’s closed space. If you want to go, build yourself a rocket and go. Just don’t ask the rest of us to waste our money on a pipe dream.
Maybe when one of our probes finds, you know, some planet we could breathe on, or a mountain of gold out there, I’ll change my tune. Until then, we’re better off colonizing Antarctica or the ocean floor. They may not be as romantic, but they are just as much frontiers, and a hell of a lot easier and cheaper to conquer.
Take the high ground. Before someone else does. Like Russia and now China.