Stigma in an Unexpected Place

While speculating about the idea of social class in AIS, I was not surprised to hear many of my classmates admit that they believe they belong to the upper class. Not that necessarily all of them fall under the North Shore stereotype, but many of them need to have a pretty high income to afford to go to New Trier.
What interests me is how uncomfortable this subject oftentimes makes me feel; I can tell it makes some of my classmates feel the same way. Our teachers are aware of this discomfort as well, and are frequently reminding us that we don't have to share any information that might make us feel uncomfortable. However, from the class survey results in Mr.Bolos's blog post, I see that nobody from our class thought of themselves as lower class. Yet, there is still discomfort as we talk about our personal social status. This leads me to the conclusion that, while there is undoubtedly stigma in being considered lower class, there also seems to be stigma in being upper class.
Someone mentioned in class that people from the upper class are stereotyped as being snobby, which is probably why some of my classmates are wary to share. However, I don't believe that a fear of being called snobby is all that is causing a great deal of stigma associated with upper class. However, I'm not sure what else could contribute to this. Could it be simply that some of my classmates don't want to make others feel bad? But would it really make others feel bad if no one considered themselves a member of the lower class? Why else could this be such a touchy subject in our class?

Update

Junior theme!!!! Woohooooo!!!!
Research has been going well! I'm currently reading The Invisible Plague, however my reading of The Price of Privelege has taken a momentary halt... The Invisible Plague is helpful because it examines the history of mental illness in the United States all the way back to when the colonies were first established. However, I am wary of some of the statistics I look at. They say that mental illness is on the rise in the United States, but I believe it's impossible to tell if they are just being more frequently reported and treated, since the stigma behind mental illness is slowly decreasing. There is no way for me to know how many Americans really were depressed if they hadn't even told anyone.
Today, I interviewed a social worker that works in the school. It was a successful interview, although it was shorter than I would've liked. She had the opinion that the decrease in stigma was the biggest reaon for the rise in mental illness. I also plan to schedule an interview with someone outside of school. JUNIOR THEME ROOOOCKS!!!

Update

My research has been taking many interesting turns. My why question is "why is mental illness on the rise as America's affluence increases?" I was surprised by how many possible answers there are to this question. For example, I've already stumbled upon the evidence of medicine as the culprit, as well as Western civilization, urbanization, and even over-diagnosing.
In addition, I am reading the Price of Privilege and The Invisible Plague. The Invisible Plague is teaching me a lot about the history of mental illness and its rapid rise in the United States. I am working on getting the movie The Road to Nowhere. I'm making great progress!