As it seems that most had some sexual fantasy or quirk about them to go along with their mental illness. To satisfy this they had to go seek it out, where as now with the internet they can find anything they want at the touch of a keyboard and with the dark web they can live out their fantasies with willing participants instead of raping and murdering people, they now can do the unimaginable online or meet up with others with similar ideals.

I think the shooters we see today are the people who used to just kill themselves when life didn’t go their way, but thanks to the popularity of other shooters they now want the same as they can still end their life but now take out others and have their 15 minutes of fame along the way.