I actually think that rebellion is never against someone in particular. It's usually against some sort of theme or ephemeral idea. If it was so specific, it would be easier to diagnose. While a teen might typically rebel against his/her parents, it's not their parents that they are actually railing against, deep down they generally need the structure, and want the structure that parents enforce (ever been free to do whatever you want as a kid? it either gets old/boring/pointless, or out of control very very fast until SOMEONE in authority steps in). Rather, it's the thought or feeling of "being controlled" or "not being independent".

Also, about your little case study -- 1000 people constitutes a large enough swath of 300+ million Americans, so I don't have a problem with 5 people that actually exist being a good enough case study.

A guess as to your observation: Do you know what kinds of jobs they've had as teens/young adults? Many of the starter jobs are related to sales, in some form or another (best buy, verizon, places teens know something tech related might work, even places like carwashes, etc), and (just spitballin here), I think the role of a silver tongued deal-maker is very popular in many upper to lower middle class and even lower class groups. Marketing seems like a natural extension of that. Also, I've always thought of marketing as the attractive, relatively business-minded person's liberal arts degree (but maybe that's just me).

Also, on self-esteem, it's sometimes something you can't tell from just looking. It's kind of their job as marketers to have very very high self esteem. If you get a pitch from a marketer, and they look like they have even the slightest doubt that their plan will fail and NOT bring in piles of cash, then you're dealing with a bad marketer.