Ian David Long (2018): Marine, Afghanistan war vet
Nikolas Cruz (2018): High school Army ROTC
Devin Patrick Kelley (2017): Air Force
Stephen Paddock (2017): Worked for Defense Dept., Lockheed Martin
Omar Mateen (2016): Private security guard, wanted to be a cop
I could go on. Obviously not everyone who serves in the military or law enforcement is prone to committing indiscriminate mass murder. But if you think the prominence of this in American cultural life is not a salient factor, you're deluding yourself