Absolute gem of a post. You hit the nail on the fucking head, so close in fact I have to ask if this is from personal experience?
I think a major issue that has perpetuated the incel problem has been the mixing of the term to mean both the cult of Incels (the killers and their followers) and guys who just can't get laid. I would say the majority of incels fall into the later group, they're just socially maladjusted men who are struggling with dating. Why these men end up here varies, personally I attribute it mostly to a society that doesn't give a fuck (and frankly is outright antagonistic) towards young men. When you have a due who is just depressed and lonely, and society treats him like the former cult-like Incel, his depression will turn to bitter resentment. And who will be waiting for him with open arms then? The Incel community of course, they will be the only people to offer him empathy and companionship, and thus he will spiral further. The extreme antagonism towards both kinds of incels is what propagates the majority of them, and the slightest shred of empathy would go a long way in fixing most of them. But of course that will never happen.
I'm speaking from personal experience as someone who was a "normal" incel. I had shit self esteem and bad luck with women, that turned into a complex. The more I was berated and the more the aggressive narrative about incels grew, the more my complex turned towards anger at people. I just wanted to be loved and to feel valuable, but despite my success in all other walks of life, I was made to feel like a freak for not getting my dick wet. I internalized that feeling and otherized myself, which in turn otherized everyone else. I felt like I was marked in some, irredeemable because I didn't touch a pussy before I turned 20. It sounds absurd, but there are plenty of dipshits like this who perpetuate those ideas.
I was in a really dark place for a long time. Never wanted to hurt anyone except myself, came close to it a couple times. Eventually I grew out of it, but it was hard to do that without a shred of support or empathy. The thing that ultimately saved me was learning to not give a single concern as to what others think about me. Made me a bit of an asshole, but whatever. Focused entirely on making myself content and what do you know a couple months later my self esteem was fixed and I was dating a girl.
To be clear though, Elliot Rodger types should be rounded up and buried alive. Speds who want to kill random people over pussy aren't worth keeping around.
We really do need a different term for the different incels though. That would be a good first step. Not holding my breath though.