75% of the life that existed OR more went extinct because of the meteor impact. And that was only 1 mass extinction. Because humans depend on lots of plant and animal resources, if something as big or bigger hit us, the odds even with our modern technology, would still be against us, because the impact alone would disrupt that technology on top of killing off tons of plant and meat and fish food sources. So a meteor defense system would go a long way in extending our ride.
https://en.wikipedia.org/wiki/Cretaceous...tion_event
https://en.wikipedia.org/wiki/Cretaceous...tion_event