There is so much death and cruelty in the world that if someone cares too much they are just bound to wind up depressed. It seems that the majority of people really only care about people that they are acquainted with, or if they witness the terrible thing in person. It's just kind of built into human nature, otherwise we would be in a constant state of grief.

Things like mass shootings bother most empathetic people, in general. It's just that life kind of has to go on, and all they can really do to try and change it is to vote for one of two lesser evils in some local or national election.

The problem is not really with the people. It's with our crappy political system that is controlled by corporate lobbyists. The majority of US citizens don't really seem to have a say. Source: Empathetic person with chronic depression.