Much political and creative energy is spent attempting vengeance against one’s childhood and adolescent enemies, if only in some inchoate, subconscious way.
Sometimes this can be fun, e.g. the movie Heathers. Winona Ryder,* ostensibly one of the “popular” crowd, is actually an attractive surrogate for the alienated teenagers in the audience, while Christian Slater’s character is the sort of witty, ectomorphic rebel that they wish they could be. He is at the beginning of the movie, anyway:
The same basic principle applies in Mean Girls. The sidekick character even says “Evil takes a human form in Regina George.” To a middle- or high-school girl, the most popular girl in school really is evil incarnate. She can and does make daily life a misery for those lower on the totem pole, who would of course act very much the same, if not worse, in her position. The last third of the movie is a revenge fantasy, where Regina gains weight, is humiliated in public and almost loses her status. Lindsay Lohan’s character also gains status by dating Regina’s ex-boyfriend.
Sometimes this isn’t fun. The Columbine High School massacre was actually the result of one psychopath and one depressive trying (and failing) to kill as many kids as possible. They were not neo-Nazi outcasts avenging years of bullying, but these myths have persisted because they fill several different psychological needs.
Many nerds spend the better part of their adolescence getting picked on for being studious, smart and having strange preoccupations. (The same applies to goths, who are probably more intelligent than average, and to similar subcultures.) When they reach adulthood, some of that anger is channeled and redirected towards people who remind them of their high school bullies, i.e. mesomorphic white men and ex-cheerleader types.
Why, then, are nerds anti-racist? Unless they’ve gone to school with blacks (and many haven’t) they may view them as their protectors against the alpha males who beat them up in high school.** That is why race realists are “that much more terrifying,” since (in the back of their minds, they think that) these people might turn their “protectors” against them. Also, since being racist is just about the worst thing you could be, it makes sense to believe that “evil incarnate” would also be racist.
*Ryder actually did get revenge on a high school bully in adult life.
**This may have less to do with protection and more to do with revenge. Tertullian famously wrote that one of the pleasures of heaven is seeing the damned tortured in hell; “diversity for thee, but not for me” may be an earthly expression of this type of pleasure.