What @ucme said.
I don’t think that evil, or even necessarily sociopathy, are behind attacks like this. I’m sure it’s plausible that some of the people involved would fit the bill, but I don’t think that’s the case in the majority of situations in which people do horrible things in large groups.
We are social animals and it is in our nature to behave in a group. When this is done in the name of good, which is the majority of the time, we are a progressive, productive, remarkable species. We have an incredible drive to be accepted by our peers and sometimes that takes a turn for the ugliest side of humanity, especially as we know that mentalities and behaviors have a potential to move into extreme territory when in social groups. This is how riots start. We wouldn’t call gorillas or chimpanzees who engage in this sort of behavior “evil,” we would consider their intelligence less evolved. I believe the same is true in cases like this. We have a much better chance of changing this type of behavior if we recognize where it comes from and why people behave this way. I would venture a guess that the majority of the people who are involved in situations like this end up with PTSD or other long term psychological effects, because they probably regret it as it wouldn’t be in their nature to act in such a way independently. This doesn’t excuse or justify the behavior, but it’s a much better explanation than chalking it up to “evil,” which feels like a cop out to me.
Will they ever stop entirely? I doubt it.