I certainly do not mean to denigrate the seriousness of the several shooting incidents (a small sample of which are mentioned above) which have occurred over the past few years or the pain that they caused. Actually, there were 30 such mass shootings between June of 1984 and December of 2012. They were all horrible tragedies which I wish had never happened, but I'm not sure how much good comes of it when, in the post-event coverage, someone (either a reporter or a relative of one of the victims) invariably asks the question "WHY did this person commit this terrible act?". A smartass like me would be moved to answer, "Because" and let it go at that. I say this because, in any event, the specific motive of the shooter is, for the most part, unknowable because in 20 of the 30 cases cited above, the perpetrators are dead, having been dispatched by the police or, more frequently, having committed suicide. In three cases, the shooter seems to have been a disgruntled employee and in ten cases there were indications that the perpetrator of the crime may have been mentally unstable and/or subject to delusions and indeed, several of them have claimed the "insanity defense".
But, no matter what the investigations of these incidents, or interviews with the shooters, have revealed, mass murder is not the act of a rational mind. My point is that the very asking of the question "why" implies that there was some reason for these despicable acts that a rational person can fathom and I do not believe that that is true. So, when you ask me, "Why did Adam Lanza kill all those little children at Sandy Hook Elementary School?" my response is: "Because he was CRAZY or EVIL or BOTH!" And trying to dig deeper than that is an exercise in futility. He did it. He was a nut case. Let's just be glad he's dead and will never do it again.