Another one: Elliot Rodger
Those are exceptionally publicized recent cases, but this isn't a new phenomenon, of course. Dylan Klebold and Eric Harris, Colin Ferguson, and Charles Whitman come to mind.
Many of them had unexceptional, if not ideal, middle-class backgrounds. However, many of them also had psychological treatment and medication histories.
Like the Columbine high school killers, they weren't murderers or serial killers who tried not to be caught. Many of them publicized off-beat manifestos like the Unabomber, except Ted Kaczynski tried not to be caught. They acted like attention-seeking political Islamist suicide attackers, but with the exception of Nidal Hasan, without the conventional script of political Islamists.
Add murderer-suicider Elliot Rodger to their ranks. He was a rich, style-conscious, good-looking 22-year-old kid. His use of multi-media to set the stage reminds me of Seung-Hui Cho. Reading his autobiography/manifesto, My Twisted World, his motive sounds like George Sodini's. Rodger suffered from acute sexual alienation, or involuntary celibacy, which is a serious life-changing problem shared by many men. Rodger's obsessed approach and psychotic solution to his problem, however, were atypical. The incongruity is that like Sodini, Rodger looked like a guy who should have had no problem getting it on with the ladies. There's a lot more to sexual dynamics than looks.
Rodger felt boxed in and acted with hopeless desperation. If just one girl had given him intimate feminine affection - not sexual intercourse, just affection - would that have provided enough hope for Rodger to hang on and prevent his "day of retribution"? Parts of his autobiography claim it would have made a difference. Other parts imply it wouldn't have been enough. Rodger's mind was trapped in a corrupted inner dialogue and who knows what he needed to break free.
It sounds like he had a psychological profile similar to Adam Lanza's with a diagnosis of Asperger's syndrome. I've also read he was extremely paranoid and heard voices, which are indicators of schizophrenia. He wrote his mother was on birth control and a medication for an unspecified illness when he was conceived, and I wonder if his DNA was damaged from the start. My armchair layman's diagnosis is Rodger suffered from schizoaffective disorder.
The proximate cause of Elliot Rodger's "retribution" is his psychosis. Of possible contributory social factors, however, the thing that stood out from his autobiography is the seeming absence of his father teaching him how to be a man, especially guidance on sexual relations. They weren't estranged, yet there doesn't seem to have been even a birds and the bees talk. A strong father can powerfully influence his son, perhaps even enough to help his son overcome a phobic aversion to approaching girls. An actively paternal, positive masculine role model provided by Peter Rodger for his eldest son might not have prevented the harm caused by Elliot Rodger's mental illness. But it might have. Add: Insight from a family friend, Dale Launer, who tried to help Rodger with his lady problems.
It's not enough to chalk this up to the mysteries of maladaptive mental abnormality. There's that, but there's also something wrong here, a cancer in the social fabric that's deeper even than the things we normally worry about.
31DEC15 add: Aggrieved HAPA man identifies with Elliot Rodger.