Short answer: "all of the above". Long Answer: The prevalence of mass shootings in the United States was is much a cultural issue as it is a political or legal one. At the root of it all is an inability to cope with uncertainty and the capacity to tolerate difficulty.

The modern lifestyle of increased expectations, convenience, and immediate gratification had created an environment where people had become so used to getting what they wanted that they couldn't handle the stress of waiting. The sense of entitlement and an avoidance of discomfort had resulted in a generation of people who had limited coping mechanisms and, therefore were more vulnerable to violence and recklessness.

On top of this, mental health resources were often lacking in rural communities leading to an inability to address underlying mental health issues. At the same time, proper parenting could help people develop resilience and emotional regulation which were key in combatting the impulse to commit acts of violence.

These societal factors, alongside the easy accessibility to guns due to lax gun laws, had created a perfect storm for the tragic phenomenon of mass shootings in the United States.