What's with the term "yuppie"?

Before you think this is OT, read the rest of this post. So, what is the deal with the term "yuppie"? Why is there still such a derisive approach to the people who are investing in neighborhoods and bringing about the gentrification that produces the construction flurry and economic health that (I assume) want for Chicago? Why is there such a (seemingly) universal derision of the typical yuppie's taste, when, most likely, yuppies are the ones who have the disposable income to put into supporting the city's fine arts? Even despite heavy attempts at peer solidarity and forum moderation, occasional references are made to yuppies, in a vague derisive attack against a demographic that are largely responsible for the resurgeance in cities. And, in case you don't think this is particularly related to Chicago, the "term" yuppie is a reactionary term originated in Chicago (I believe, in fact, the Chicago Tribune, which I suppose is cynically fitting), developed in like the 50s and 60s and championed by blue collar neighborhood groups against the growing, educated, socially mobile class. So it speaks of, and still used with the connotation of, a midwestern reactionary attitude that is not befitting of anyone who wants to be a citizen of a world city.>