Edit: I'm not saying anything negative about the female side here, just the male one
On one hand, you have fanfics, kpop Stans, fandoms, Sanrio, etc.
On the other you have literally 4chan, literally reddit, circle jerks about muh superior white music genres like metal, modern rock, and being "cultured" by liking suffering porn with socially conscious hip hop, Roman history, WWII history, military obsession, geopolitics obsession, gamer shit with n-words and Japan stuff, some weird shit with obsessing over your body/facial features to be the perfect Eurocentric ideal, etc.
Also shout-outs to pro incest and pedo anime culture
In the words of a friend who agrees: White men just cannot be trusted to be left alone together on the Internet
Most of the people I've known who were into anime were women, some of them are even anime artists. In the 00s, I only knew about anime because a girlfriend of mine (platonic) was into it and tried to get me into it and I thought it was mostly something that only interested other girls. I was aware of Sailor Moon and knew girls who had posters of it in their rooms, but never knew any males who admitted to liking it so hearing that anime is thought of as a guy thing is still strange to me.