It's an interesting thing how crime rates in the US peaked right after the fall of the Soviet Union and then went into deep decline: It's as if having the visible external enemy was the factor that allowed it to increase, and the post-Cold War paralysis deescalated this process. The Soviet bogeyman was replaced in turn with terrorists, but this too is increasingly seen as a domestic issue of "right wing militia v. antifa", lacking in credible affiliations abroad as the Mid-Eastern interventions have wound down.
And that is perhaps the real source of the frantic polarization: Look anywhere, just not in the mirror.