Even if you look at it from a psychopathic killer perspective, ER threw his life away killing random mediocre people. Unlike AM and others, none of his victims were particularly attractive, and most were men. Which is especially sad since while AM basically rolled the dice and had no real way of knowing who he was actually killing, ER's method provided significantly more control over who he could target and he still underwhelmed.
But I guess you generally do it so that your cause gets more attention than anything else (kill someone important, everyone focuses on them. Kill someone you hate, everyone focuses on the personal grudge instead of any broader intentions). Rodger was a narcissist, he definitely wanted the massacre to be all about him and his message.
But make no mistake, if you think you're an incel crusader but all you actually do is kill Beckys, kids, and other incels, that's a flop.