True crazy people are numerically rare. (unlike mildly eccentric types whom most of us can find by just looking into a mirror.) Funny thing about them though, is that they seem able to sniff the air, find each other and then gather in clumps. This explains whycome you ran into three of them at the range at the same time.
Your young niece learned a valuable lesson finding out early that, yes Virginia, there really are crazy people and not just something made up for television. Now, she will need to learn that, in any substantial gathering of people, the Great Pumpkin will seed at least one loudly irritating crazy person just for entertainment purposes.