If you look at the surface of the moon it is obvious that there is a lot of stuff whizzing around and smacking planets. As we map from satellites with multiple types of detection systems you can see craters on earth that have been overgrown or beneath the sea.

The bit that people forget is that every time there is a near miss, the gravitational pull of the earth is making the next orbit a little bit closer, so those misses will be hits at some point.

Too bad no one wants to do anything about it.