We have an extremely exaggerated sense of self in America. This hyper-individualism that seeks to lay responsibility solely on one person. Adam Lanza is just the latest example of how pathetic the mental health infrastructure is in this country. People who are obviously mentally ill go without treatment because "it's their problem" and "why should my taxes go to help some (insert pejorative here)?"
Actually, the health infrastructure is pathetic because it's really fucking expensive. It all boils down to money. Who's going to pay for this, and what is the priority for this measure.