I think it has increased with the social media extremism that has been pushed through politics also, with a lot of far-whatevers polarizing on topics that make people scared and feel threatened.
Violence has always been around and many people have been heavily exposed to it in reality, but not become violent themselves. But at those times, there were social communities and family units that built connection. Now, people are isolated, alone - but still have human desires.
Maybe I'm starting to go the way of the hermits lol!
I think many have, which also means that the streets are filling with psychos.