You don't need to be extremely bright to realize that it's easier to burglar a home with no alarm system and cameras than one with. And if your neighbor doesn't have cameras, but you do, many home burglars are going to be smart enough to know that it's better to not be seen on camera. I'm sure there are some who have too low IQ/too high to realize that getting caught on camera is a bad idea, but at least it's gonna work on some.