Humanity will have no choice but to try to escape the solar system at some point. If it makes you feel better about it, think of humans as natives of this galaxy.
In the shorter term, humans can either *choose* to live in a more sustainable manner in this solar system or the choice can be forced upon them.
Personal judgment --- resources would be much better spent on sustainability rather than escape at this point in time.
The shelf life of complex life on Earth is probably closer the end than to the beginning. Still a lot of time left from our perspective, but we have to save ourselves -- and the legacy of complex life on Earth -- sometime.
0: https://en.m.wikipedia.org/wiki/Timeline_of_the_far_future Expand "Lists" and search for "photosynthesis".
Things will improve here on Earth once we realize we're stuck in this solar system. Forever.
I don't think this bleak defeatism is warranted at all. It feels like a projection of hopelessness about local affairs.
Surface-wise, planets are actually non-ideal. Habitats are where it's at, baby. (E.g., O'Neill cylinders or, more fancifully, ringworlds.) But we probably can't ever build those cuz we suck! T_T Waaaah!!