What's the Point of the Shooting?

"There are people we should be really fucking angry at and his father is one of them," she said. "His dad doesn't seem to have been a great dad, right? His dad was like using when he was a kid, his dad was abusive, rewarded his violence." She added: "I think we all know lots of people who are raised in those climates who didn't go on to shoot up a nightclub"