The men's rights stuff tells them they've been sold a lie/raw deal by society, and that they can get power, success, etc. by rejecting that narrative that didn't work for them. Yes, this involves a lot of fear, misogyny, etc. but at it's core there is the message that it's your own fault, and you need to take responsibility: learn to set boundaries, work hard, prioritize and communicate your own needs, develop vulnerability and emotional intelligence, etc. Old self help books that really work are extremely popular in these communities, and these men support and coach each other in working hard to apply these lessons in their own lives. Those books predate "incel" or "mens rights" stuff and themselves have nothing to do with it.
I grew up with these same issues, and found advice that helped me because it had been popularized and made visible by these "men's rights" groups. I wholeheartedly reject the misogyny, narcissism, and fear based manipulation these groups use, but I also wholeheartedly accept the idea that most of my problems were caused by myself, and I can do the work to fix them by doing the internal emotional work, learning to set boundaries, etc.