The wealthy class of teens often cruelly capitalizes on their superior access to money and social power which builds animosity within the less privileged classes. The wealthy class develop among themselves a system of dress and demeanor that is very much akin to their fraternity and sorority counterpart which eventually matures into the business and country club community of adults. Preppiness, in such a way, is really the earliest exhibition of the wealthy attempting to subvert and dominate the poor that the average American experiences while growing up.
Dirt poor bastard wearing clothes from Salvation Army: "Dude, that guy's wearing a pink sweater and looks like a cocky prick."
Principal: "Now that's no way to talk about your fellow classmates. Zack Morris is one of the wealthiest students at this school... although he is known for his hillarious shinanigans."
Dirt poor bastard wearing clothes from Salvation Army: "Look, he's got that smaller poorer kid in a headlock."
Principal: "Oh I'm sure that kid deserves it, but you can see me in detention for using the curse word, 'prick'."