This is not pleasant reading, but the author accurately observes that there has been a change in the behavior of Americans. Nowadays we too often see Americans acting out with violence against others, regarding their fellow citizens with suspicion, behaving toward others with callousness, and uncritically accepting views from media authorities. I noticed this also after returning in 2006 from living four years mostly outside the US.
Violence, always violence. From infancy, Americans are conditioned to enjoy violence, then lured or pressured to support it at every stage of life.