People should spend money on space exploration just for their safety. All of our human species - over 7billions of people, lives in one place, on the one pice of rock surrounded by unfriendly space. We are still exposed on asteroids and cosmic crap flying around Earth. That situation on a cosmic scale looks like looking for trouble. If we live all together we only need to have one enough big incident to annihilate the all of humanity. Let's take a look on the ants. Their world is an anthill, they live in it and do their ant job. But one day forest within they got anthill burns down. It was as big incident as id destroyed all of them. But ants are smart and made many anthills in many forest, so annihilation of one anthill doesn't mean the annihilation of the whole species. Earth is our anthill but on much more scale, so we should spend money on space exploration and as fast as we can split population to many planets to avoid any treats from space.