I asked my counselor a long time ago about people you see talking with themselves, imaginary others or God on the subway, streetcorner, etc. He has experience with this sort of person and I asked him something to the effect of 'Are they suffering? Are they aware of their circumstances?' and he said that those who are far gone into imaginary worlds typically don't suffer much in the way that we understand it. He said that those who suffer the most are those to whom our shared reality is just out of phase enough that they get to perceive it but not participate in it wholly.
This guy had been going along with the big game we've all made up between ourselves. I stay in my lane you stay in yours and nobody has a head on collision on their way to work or their parent's house or church or whatever. Play your part, try to make your way, try to not hurt others, try to bring some joy into the world. And then something changed, and I don't think we will ever know what it was exactly that pushed 'Rich' to do what he did today. My suspicion is a long, deep, quiet suffering.