The way I see this PUA > red pill stuff, it's basically cause and effect. Any guy born after the mid - late 70's was raised on the idea via mainstream media that to get the girl you wanted to get, all you had to do was be really nice to her, be a really good friend to her, help her out whenever she needs it, and most of all "be yourself"and one day she'll realize she's in love with you. Why every piece of pop culture post 1980 picked up on this idea, I have no fucking clue, but they did, and so you got a couple generations of guys who were doing the exact opposite of what they had to do to attract the woman they want. I'm sure climbing divorce rates leaving a lot of guys without enough access to a decent father figure didn't help either. Not to mention feminism and it's various toxic narratives about gender relations. But it's the media, more than anything else, which was the real problem I think. A generation raised on movies and TV shows where the quiet nice guy gets the girl over her jerk athlete boyfriend, despite the fact that nothing changed about him to make her more attracted to him than she started out. She just changes her mind so they can live happily ever after, because that's what the plot demands.
Then these guys, they hit 16, 18, or 21, or 25, (the age depends on their intellect and general gullibility) and they're not getting laid, and they're not getting relationships, they realize that they were raised on bullshit, that the way they were taught to attract women is totally ineffective. And so they get really fucking pissed off. Of course they did, they'd been lied to their whole lives and it ruined their chance at a healthy sex life/relationship. If instead of shoving bullshit down their throat, the media had told boys that the best way to get what you want in terms of sex and relationships is to be healthy, fit, reasonably well groomed and dressed, confident, interesting and living a life of some kind of purpose, then PUA/Red Pill would never have occurred.
But it did. And yeah, because these guys were angry, a lot of sexist (and ultimately self destructive) crap got into the whole ideology, especially with the PUA movement (which for the record - not a fan of. Not really a fan of a huge part of the Red Pill stuff either, although the basic self improvement stuff I can get behind). If you were raised in a culture that told you that you'd achieve happy relationships if you would just 'be yourself' and 'be nice,' then you did exactly that and you got absolutely nothing, of course you'd blame the women. After all, you're doing everything you were told to do, but the women are still ignoring you, so if you don't have the intelligence and self awareness to examine the media message, then you're going to think the fault is at their end.
I've seen a lot of guys go through it, they think they'll teach themselves the right techniques like it's a manual and then they'll be drowning in pussy. But it only works (ie, leads to a satisfying outcome) for a minority. Most either realize that a life of meaningless promiscuity gained through memorized lines and fake personas is only marginally more satisfying than what they had previously, or just don't have what it takes in terms of confidence and lifestyle to pull it off.
Then Red Pill evolved, which was basically, in theory, what was missing from the PUA movement - a breakdown of why men were having such a horrible time attracting women and the changes they needed to make to themselves to fix it and reach a satisfying sex life/relationship, as opposed to mind games and rote memorized lines to sleep with dumb bar chicks. Problem is that a lot of that anger is still there, and a lot of that PUA idea that it's all about techniques and control, instead of developing yourself into someone that women want to be with, so it ends up with some good advice for men who aren't getting what they want in terms of sex/relationships, but it also ends up with a lot of misleading advice which is going to lead them to developing attitudes that will ultimately work against them (although not as bad as PUA in that regard), or attracting the kind of women who fall for the manipulative crap - who aren't the kind of women you want to be with anyway.