I actually wasn't being flippant - at least not totally. I've read over and over that he most likely killed them because one or more of them rejected him. By rejection, I'd take it to mean he asked one or more of them out or to have a cup of coffee with him (rather than outright sexual rejection, because i think he might be a bit tactless, but not so brazen as to ask a stranger to have sex with him right away). Of course I could be wrong.
As for being misogynistic: why would a man seem to have good friends who are women if he genuinely hates women? Granted he was apparently bullied by girls when he was younger, and I can see anger, resentment and possibly psychological / emotional damage due to that, and I've wondered if boys bullied him too. Regardless it had to have an impact on him, and yet his friends from back then were his friends, and they've said he did have a small group of friends (which changed to another small group of friends when he started doing drugs). Same thing when he was in college (based on what we've been told). And a few said he'd do anything to fit in. So instead of hating women, I'd be more likely to believe he might resent and dislike people in general: or more specifically how people treated him.
A knife might be more personal, but it's quieter than a gun and faster than strangulation - and who ever did this, was apparently fast and effective. But I do see... not sure how to word this so it's not too much... It's like if you're really angry and you throw something at a wall. The act of throwing feels good and helps reduce the anger. And I can see that using a knife could do kind of the same thing. And to stab that many people, there would have to have been a lot of anger. I don't think I worded that very well, but again trying to watch what I'm saying.
I don't know what motivated the killer or what made him act on that particular night. Even if the house was being watched, what was different about that night? Something was, and IMHO, like I said, I don't think it was because someone said no to a date or a cup of coffee. That might make someone throw something at a wall, but it doesn't seem like it would make them kill four people. Then again, people kill other people over road rage and that doesn't make sense either. I can only look at what we've been told so far, and some things I can see and others I can't. In the other post, I mainly focused on the things I'm not buying - not at this point. Not based on what we know.
All MOO, IMO, etc