As a person who grew up with 5 dogs in one household, which is way above the recommended amount because when they're left poorly trained in that amount they act like wild animals, I've never seen one of those dogs hurt someone out of nowhere. The only time anyone got hurt by them was while trying to break up a fight between them, which only happened twice (me being one of them) and that dog immediately let go of their bite once it happened and calmed down. That all being said, it wouldn't have happened if my family raised them properly. I was still a kid for the majority of their lives, so I barely had control of it up until I was a teenager. In any case, they still were fairly good dogs, it was just that the males used to fight each other, and that was only due to my family raising them poorly. Other than that, they never purposely attacked a human. I'll detail all this more later if I need to, but I need sleep for the moment.