What is WRONG with people?

This is hard to write about. I'm really upset about what happened to that little girl, the one who was attacked at a party in NJ by at least 12 men and teen boys. I can't even begin to imagine the horror that she went through and will continue to go through for the rest of her life. And, what is WRONG with people. Maybe the attackers were abused as children, maybe it was the perfect storm of society giving up/poverty/misogyny, maybe they fell into madness as it started and then others thought, 'Oh, what the hell.' That whole thing of accepted group behavior is as strange one. Someone else started the attack and then no one did anything about it and this sent a signal to the crowd that it was ok. I've read studies about this peculiar human behavior and most of these studies show that people do nothing or join in. Look at the Holocaust, how was that allowed to happen. I guess I'm just looking for some kind of explanation about how a 15 year old girl can sell her sister and it's accepted at this party.

I cried as I read this story and then I cried again. I didn't mean to click on it for Christ sakes. I was doing a search on Jerry Seinfeld's TV dad, who just passed away and this, horror popped up. I felt it like a stab to my heart.