Geeks are bullied because they violate gender roles, are privleged
I find this argument persuasive.
How many times have you heard/seen the cliche about geeks being bullied only to go on to rule the world? That's a class thing; it's taking solace in the idea that a geek will not remain with the plebs.
Though in this case, the writer found that they came from a background and maintained interests that gave them advantages down the road because it gave them cultural capital. Cultural capital is the idea that there are things beyond finances that can influence social mobility (the ability to change class.) We're talking education, intellect, the way you dress, the way you speak, the way you look, amongst other things.
To put it simply, when it comes to class, a stereotypical geek might have good chances of moving up in the world.
In certain sects of geekdom, the tie between class is particularly clear. Some hobbies require a good deal of money to keep up with, and games are a good example.
Beyond class, there's also the issue of gender and homophobia. If you're into games, comics, D&D or any other geeky thing, those hobbies operate outside gender roles. You're not, say, learning domesticity if you're a girl playing shooters. You're not being manly if you're constantly lost between the pages of a book instead of playing football.
Class and gender roles are difficult, sensitive subjects. Perhaps that's why we don't talk about these things—I fear that the narrative of being bullied simply because you're a geek and you really like things is simple and attractive when trying to explain the bullying.