I think it is essential for the long-term survival of the human race that we migrate off Earth eventually and start colonizing other planets. Until we do, the human race will remain vulnerable to extinction-level events like nuclear war or another asteroid on the scale of the one that killed the dinosaurs. But there's really no rush, this should be an ultra long-term multi-generational type goal, which probably will take centuries to realize. Trying to rush it and / or use it as an excuse to ignore pollution / climate change is incredibly irresponsible. Let's fix the problems we have here at home, and then more resources can be devoted to space exploration.
But I don't want to see space funding completely slashed. I love science fiction and the romanticized fantasies of living on other worlds & traveling around the universe. I want to see Mars exploration proceed but with realistic goals. Baby steps first. I'm very supportive of a manned mission to Mars sometime in the next decade or two. But not to start a colony. First we've got to get there, put people on the surface, and just see what it takes to do that. Something like the Moon landings to start off (and on a side note, it's an absolute shame that we haven't gotten around to sending people back to the Moon even).
If I live long enough to see a manned mission to Mars, I will die a happy man.
This! We're naturally curious and its so understandable when we devote lots of resources to explore the world around/beyond us... However, this shouldn't be at the detriment of destroying what we have now for what we might get in the future...
I however don't agree that we need to colonize other planets to achieve peace. Being human naturally means we're exposed to conflicts.. There are several other (and economically viable) means of reducing conflicts and maintaining peace. Besides, we're more exposed to planetary accidents when we leave our comfort zone - earth. And here's a toast to an additional 100 years to your current age ;)