We should consider the likely alternative - Americans are actually pretty nice to each other, all things considered. It is really quite impressive what American grass roots organisations can do if people let them. Trust in institutions is low because the institutions are being exposed to the harsh light of Very Good Communication and it turns out that bodies that rule by decree are kinda corrupt. That should shock people, but it doesn't represent a radical change in the status quo.
There are serious economic headwinds that someone needs to do something about.
It seems a lot worse in the disadvantaged socio-economic parts of town. I think there's an attitude everyone having to "fight for mine" and "what has society ever done for me" and in response not caring for it.