Thanks. I expected the downvotes. But it breaks my heart that we have such a beautiful planet and we treat it like a trash heap, all the while dreaming of Mars and whatnot. Let's put our own house in order before we go off travelling.
Those same < 10 000 people probably doesn't know nor have the ability to fix all the problems on Earth, but they might be able to get to Mars.
Parent: See that little blue dot in the night sky? That’s Earth.
Child: What is Earth?
Parent: Earth was the planet of our ancestors, before people came to Mars.
Child: Who lives on Earth now?
Parent: Nobody. It’s a dead planet. The actions of rich, selfish people destroyed it.
Child: How did the rich, selfish people destroy Earth?
Parent: They burned it up as fuel, getting to Mars.
That proverbial man who plants trees knowing he will never sit in their shade is proverbial for a reason.. it's an amazing and heartwarming little saying because it's a contrast to how we generally behave, as individuals as well as organizations and masses. We learn from repeated catastrophe.. sometimes, maybe. But this problem is not one we can have a lot of attempts at solving. Right now we are still moving into the wrong direction, and probably even accelerating.. sure, hitting a wall can make people change their direction, but not if it breaks their neck, so to speak.
I'm not enormously optimistic. I'm just saying that compared to interstellar travel, avoiding fossil fuels seems like a fairly small problem.