why do we live like that?

1. We must maintain the tradition of the journey to lead our ancestor to the Afterspace. 
2. It's not the planets that are cursed - it's us. We carry the weight of millennia of sins. We are too corrupt and impure to taint the worlds with our presence.
3. The Vectors were given to us for a purpose. We must follow them no matter what. And when the time is right - we will know the reason.
4. The Destroyer preys upon mankind. We must remain on the run.
5. It is not important why the Pilgrimage has started. But now the journey is a crucial part of Paths of Universal Interconnections. We've carved our ways, the Paths that aren't ours anymore. Now it's our duty to continue the work.
6. The Null-Drives of the Worldship are in fact powering the simulation of the universe. If they cease to operate - we cease to exist.
7. Vectors make an enormous sigil, unfathomable for mortals. Artificial Gods are constantly reshaping and perfecting it. We just test its integrity.
8. If you stay on a planet for too long, you wake up. And the reality is much, much worse than the Dream World you experience now.
9. There are no planets, and the moons you've seen are just asteroids. It's just a mystification. Hallucinations caused by... someone, maybe Synth-Gods, to conceal something. Something sinister.