They have no idea due to the fact much of the material/objects in that region are undetectable due to it’s size.
Well cripplecreek is a pretty smart guy, but I’m with you on this one. If there are large asteroids we can see then, given the nature of the Asteroid belt, there are smaller ones we can’t see. So maybe the larger ones are a million miles apart but the smaller one could be closer 100’s-1,000’s maybe? I know we have sent missions into the asteroid belt but not many missions and the missions have been to very large asteroids that have probably swept their orbits clean of the little rocks. Beer time, later all.