It's not unusual for people at a concert to be drunk and/or high on a variety of things. It enhances the experience. The medics ran out of naloxone before the show even started. Many of those in attendance were probably pregaming all day in preparation for the event, and the next day were probably wondering WTF happened. Out of the 50,000 concertgoers, how many fit that description? It wouldn't take more than a couple of thousand drunk and high people to cause mayhem, particularly if they are being egged on from the stage. I'm not defending the behavior which was appalling, I'm just pointing out that there was more at work there than people being inconsiderate and feral. When someone gets loaded enough, they will in fact not know how to behave anymore. Of course screening out ticketholders who were inebriated at the gate would have caused a riot.