What are the reasons behind you think mostly Hermione fans are so hateful towards Ron?

I have always noticed it's mainly the die hard Hermione fans are biggest Ron haters in the fandom. They mischaracterize him in every way imaginable to prop up Hermione. Why do you think this is the case?

Are they threatened by him that he is clearly a more well written more complex character than her? We have detailed explanation of his trauma and character arc while She is literally just a self insert of women in fanfics.

What are your thoughts?