I see this culture of narcissism as a contributing factor to these mass shootings...
I think that was one of the conclusions he was leading us to make through this article, and I don't believe it's unwarranted.
If a child is ignored long enough by a sufficiently large portion of his or her peer group, he or she will tend to act out in a very large way to gain popularity, or in this case notoriety. Girls tend to attempt or fully commit suicide, while boys tend to lash out violently.
This is taught to every Freshman psych major in every major college in the US. Having minored in psychology, I can tell you first hand that the Lanza situation was textbook masculine "peacocking" for notoriety. He was likely a poor video gamer and a social media outcast, so he resorted to physical "real world" means to enact revenge on those who "dissed" him.
Once he realized what he'd done, he saw no way out but to kill himself. Facing the public and the scorn that would've been visited upon him was more ghastly than any video game he'd ever play.