Am guessing just another sensitive young guy who snapped at the ugliness of so much of the American way. Likely thoughts of suicide too, i'd guess. Knowing he would make his mark in history he could well have a smile, warming to him, as he went. The totality of it all is very sad.
It was Plato who said, “He, O men, is the wisest, who like Socrates, knows that his wisdom is in truth worth nothing”