> Look at how we are (mis)treating the environment
It took the realization that we are living on something that's not flat, and actually sharing the same sphere, to make people conscious that we are at risk when damaging the environment. This is linked to everything we have learnt through our exploration of space and the fact that we could NOT find find life so far on any other planet in the solar system.
Not sure why you think it's no so important. Actually, it's the other way around. In order to better protect our environment, we need to do more research to better understand the climate models of other worlds and make correct assumptions on ours in the end. If we only study a system with n=1, we can never be sure about our predictions.
What I'm pointing at is that space exploration is not as big of an achievement as fixing "bad human tendencies", however, strangely almost nobody is talking about that. Instead space travel for many people is becoming some kind of silver bullet for humanity's future.
Populating new places can enable a new start and experimentation with new forms of social organisation. Escape from the momentum of tradition.
But that's just speculation, right? It's actually not, because we've already seen demonstrations of this, like the founding of the United States and the democratic system they put in place there.
(I heard this viewpoint from reading Robert Zubrin's "The Case For Mars" https://www.amazon.com/Case-Mars-Plan-Settle-Planet/dp/14516...)