Of course, I'm basing that on his autobiography which might be nothing but bullcrap. I looked through it, and the takeaway is that he was a sullen, jealous coward his whole life--but sufficiently introspective to write 137 pages about that life in which almost nothing happened, and nothing at all happened that he himself instigated. You know, until the end. Note also that the bio was coherent and competently structured, whereas in his videos he's barely able to sputter out a normal-sounding sentence. Psychopaths tend to be eloquent and charismatic.
Too bad there isn't a history eraser button we can use to retroactively deny him fame for this.
There is also this part:
"I am Elliot Rodger...Magnificent, glorious, supreme, eminent, Divine! I am the closest thing there is to a living god."