To expound on your final point - about how a certain type of man may look to Mangione as opposed to school shooters:

It's really worth noting that almost all school shootings can trace their origins to the example set by the Columbine shooters, Eric Harris and Dylan Klebold. It may be difficult for people to remember, but in certain circles the reaction to those boys wasn't entirely negative. To a certain type of asocial edgy boy they seemed badass, particularly that security cam photo of them w…