Its a generational thing. This whole narrative traces back hundreds of years, but the recent threads have been - poor blacks working labor jobs, the industry died, the whites fled, the city ripped out their streetcars and means of getting around, and they were still here. So they turned to what was left - drugs and crime. The violence was less prominent in the start of the decline because the transition was slow. Jobs gradually lost, people gradually left. The ones who stayed were the ones who participated, enabled, or profited from the emerging culture of violence. It consumes everything else until its all that is left. Kids today are born 5+ generations into this shit.