It has absolutely nothing to do with guns or gun control.
It has everything to do with morality and self-control.
American civil society existed quite well with gun ownership until the advent of “Progressive” Ideology and its foundation of Moral Relativism and the accompanying Entitlement Mentality.
There have always been instances of extreme violence where someone has no self-control, but the tools used to express that violence were just that: tools. The violence was caused by lack of self-control.
The rise in frequency and its spread is, I think, indicative of social decay from the erosion of civil society’s moral foundations.
The teaching of self-control and respect for others has been replaced with the teaching of self-gratification and an Entitlement Mentality that professes that “The ends justify the means”.