The scientific consensus on the extinction event that wiped out the Dinosaurs is a massive Asteroid Impact. Humans would not survive a similar event and we would be wiped out quickly. This is one reason why it makes sense to invest in technologies to allow for travel in and safe habitation of space.
That money could possibly be spent more efficiently, with more scientific impact, on unmanned missions. The vast majority of our empirical scientific knowledge of the solar system was acquired using robotic spacecraft.
Current space technologies makes manned space missions very expensive and impractical. Money could be better spent on unmanned missions and R&D before manned missions become feasible.
There are many problems that require funding on Earth. We should not spend money on space exploration when we have issues such as poverty and hunger on our own planet.