Rebecca Greenfield follows the phenomenon:

At first it might surprise you that smart, skilled men would act like such louts. But this has nothing to do with skills or brains or education. It's about power. Specifically the power to throw a party. "We got invited to a party in Malibu where there were naked women in the hot tub," brogrammer Danilo Stern-Sapad told BusinessWeek's Douglas MacMillan. "We’re the cool programmers." Note how "cool," in this sense, has a direct correlation to entree into a exclusive party with hot women? That's pretty much how fraternities operate.

A perk of going through that gross pledge process we heard all about from Dartmouth's Andrew Lohse, as detailed in Rolling Stone, is that frat brothers hold the key to big campus parties. They get to decide who comes in. They provide the booze and the "chicks" follow. Once lowly freshman, begging to get into these parties — at least at my college, non-Greek men had hard times getting into these bashes unless they came with packs of women — these now powerful guys turn into bros.