Bullying and Hate have become worse, especially since the advent of Trumpism coupled with social media.
Of course, perpetrators of mass shootings are mentally ill.
But, it is more about the shooter making a statement -- flipping the tables and in one moment, becoming the powerful, the decider, the avenger. All these perpetrators view themselves as aggrieved victims of life/society, justified to unleash death and destruction. They live in their own "isolated" world.
Until communities and the nation do a better job of identifying these folks, and intervening in a meaningful way, we will continue to witness these mass shootings. It starts with every citizen "being on the lookout" for troubled people in our neighborhoods, our workplaces, or schools. Many families/households lack the wherewithal to engage their own loved ones, preferring to ignore the reality of the brewing storm right in front of their eyes.