WHAT THE FUCK HAS BECOME OF NERDS?! I mean honestly, why have nerds become such deranged people in recent years (this series is evidence of that)? Do you see the kinds of crazy stuff that goes on at cosplays and conventions and stuff? Sure, nerds have always been somewhat socially awkward people, but honestly, the kind of behavior and things nerds get involved with in this day and age is just downright disturbing.
Well to be fair, the show picks the people going to be on it, and they're gonna pick those who are "stereotypical" nerds only jacked up to 11. Though overall you could say as nerd culture has become more mainstream that certain nerds will isolate themselves more in order to be a "true" nerd.
There's also the case that, like most reality shows, what happens is heavily edited. Interviews with the Nerds have indicated that the atmosphere was often fairly convivial when people weren't actively competing, and some of them (most notably Danielle from Season 1) have complained they were edited to appear to be more of a Jerk Ass than they actually were
Conventions and such are an opportunity for nerds to go all out and indulge in whatever geeky pursuits they're into, it's all in good fun. That's probably the mode the nerds participating in this show are in.
Not all of the nerds are "crazy nerds". Katie from Season 2 was pretty normal except for her purple hair, and Xander from the same season was also relatively normal. You have to take into account that this is TV, and the more outlandish the nerds are, the higher the ratings go. It wouldn't be as much fun if you just watched a bunch of people who just kind of liked Dungeons & Dragons or Doctor Who or math.