Consider this attack
No gun involved, just random violence without conscience directed at an innocent, largely helpless man.
I will repeat: the places in this country with the most guns--rural areas--have the lowest crime; and the large cities that SHOULD have the lowest crime rates, if guns caused crime (since they restrict gun ownership) are the most violent. They are violent because they are violent, not because they have guns. London is more dangerous than New York.
To be clear, major American cities like Detroit, Chicago, and New York have not always had this sort of crime. 60 years ago both cities were relatively peaceful, even though they were densely populated and even though there was much poverty.
Cultural factors alone explain these things. My view is that lifelong saturation in violent media breeds moral midgets, whose sense of empathy is dulled to the point of non-existence, and who are taught to revere power as expressed through violence.