Again: as sooner we start our resettlement to other star systems - the better.
Perhaps one day our technology will advance to where we can create some kind of AI or AI/Human hybrid with a non-fragile body that can withstand zero gee and space radiation, but then you get into this deep existential thought of what it even means to be "human". I mean maybe Humans were never meant to colonize space, maybe our "job" as a species is to "create" a species that can, though.
I love this stuff.
Maybe we should make our ecological footprint steady-state sustainable, first.
Given the impulses of people in power now, coupled with whatever steps the future takes to make Earth sustainable, it's hard to imagine a future government allowing people to leave. It would, after all, be setting up a competitor. Paranoid, you say?
Imagine an English king c. early 1600s having a vision of the descendants of his loyal colonists rebelling 170 years later. And the nation founded by the rebels eclipsing England 130 years after that. History might have turned out differently.
The good news is that thanks to France and Spain, the English king had little choice - he had to oppose France and Spain everywhere he could, or risk losing strategic advantage.
There is nothing paranoid about that.
Evolution is not some magical 'forward' direction where every species becomes more technologically capable, or even more dignified.
It might be true that our species' now has a limited opportunity to become multi-planetary.
The first person to get to the moon was Korolev, and he would have continued rotting in a gulag had the urgency for a space program not been there.
And before you say the US is so much unlike Russia--our competing Vanguard program should, from an industrial standpoint, have won, but it was a massive failure, and embroiled in politics of its own.
Humanity needs competition to keep us honest, in the same way that the veracity of ideas needs to be tested by experiment to keep them honest.
Just take resources from military spendings and put them on both tasks. But right, humans need to learn first how to trust each other...
As one wise gentlemen in Russia once said "большая беда нужна" / "we need a big trouble" for all of us to work on such global task. Is this the only option for creating humanity deserving motivations? Not a star but [relatively] small asteroid on crash course with Earth, are we ready?
We already know at least 5 extinction events on the Earth : https://en.wikipedia.org/wiki/Extinction_event#Major_extinct....
But no proven contact with extraterrestrials.
Probably because life forms on other planets didn't care at their time - didn't pass the Great Filter : https://waitbutwhy.com/2014/05/fermi-paradox.html