Misogyny is a very real thing, even ancient scholars had documented it. Ancient Greek philosophers had said that misogyny is caused by "fear of women" and considered it a disease for example. Considering how sexist the ancient Greeks generally were, I doubt they would have documented it , if they didn't notice it as a real thing.

In several myths and religions women are also often portrayed as the root of all evil. In the ancient Greek religion for example, it was Pandora who opened the box that caused illnesses and death. The Greeks say that "fire, women and the sea" are the three evils. Similar elements can be found in most other cultures. Why did the highly patriarchal Greeks feel the need to highlight the female evil? Women were literally property in Greece, except maybe from Sparta after all?

In my opinion the Red Pill sheds light on why "females are the root of all evil" is a common element in many cultures. (not TRP sub obviously, since they fall to the same mentality of demonizing female sexuality quite often. Just TRP theory in general)

Misogyny is hatred of female sexuality. It's as simple as that. Female sexuality means that certain people are going to be the "losers" who never get to reproduce. People hate that and that's why they hate women.

People are literally calling for women to be killed now. http://www.debate.org/opinions/should-we-kill-all-women What would cause such intense hatred? Women don't control the government, most politicians are men. Women are not the most powerful in society, most capitalists are men. And misogyny has been a thing before women even had any power in society at all. So why does such intense hatred exist, to the point where many people have historically felt the need to demonize women?

It's mainly hatred for female sexuality. That is my theory. Men who are misogynists hate that they have been left out of the gene pool. Women who are self-hating misogynists hate that they feel their nature is "unfair". It all comes down to hating hypergamy.

To sum up, misogyny is caused by hatred of female sexuality the vast majority of time.