I can't say that I 100% understand misanthropy, but IMO it's way worse to single out a group and treat them differently than other groups. Whether that takes the form of racism, sexism, homophobia, etc. Generally I think that kind of behavior stems from people thinking that they are better than other people, therefore people "worse" than them deserve to be treated like garbage. And I just despise that mindset.
If someone hates me because of something I have in common with literally every human on the planet it doesn't feel nearly as personal as if they hate me because I'm different from them in ways that I can't control.