Well....... I'm on the other side of this fence and I must, respectfully, disagree.
The human species are explorers. We have a natural curiosity to find out what else is out there; and that curiosity didn't start with space exploration.
Whether you're on the creation or evolution side of our beginnings, most folks can agree that we as human beings started our journey in Africa or the Middle East. From there we spread out across Europe and Asia and eventually to the Americas.
During the age of "enlightenment" known as the Renaissance, European governments spent copious amounts of money funding expeditions around the globe. There was plenty of poverty at home at that time just as there is today, but they felt there was much to be gained from the investment; raw resources, shorter trade routes, etc. Granted, they took what they wanted by force which has left a permanent black eye on their "enlightenment" but they discovered that there was much more to the world than they ever could have imagined.
I view space travel in the same way. There is so much out there in the vastness of space and we don't have a clue. There are opportunities and resources that, given time, will be explored and harvested economically. The recent success of the Space-X reusable launch vehicle is the first step in making that possible. Up until this point we were basically throwing away our car every time we took a trip down to the store. That has now changed and traveling to space will get a whole lot cheaper.
There is one more point I'll put forth for the investment in space travel.
Terra-Firma is a bit of a misnomer. Our planet is fluid and ever changing. There have been extinction events all through the earth's history. Species have come and gone. Mankind's arrogance implies that we're immune to such things. It may be 10, 100 or 1000 years but I have no doubt that it will happen again. Maybe I have my tin foil hat on but it seems to me that if we spread ourselves out into space we have a much better chance of surviving as a species in the event of a global catastrophe.
But hey, that's just me. YMMV. 