it is the manifestation of the culture of consumption that has been relished by our mass media. movies, songs, social conditioning and everything seems to lead up to people divulging that sex should occur.
yes, some people do think that it's cool and people that young don't have enough experience to know about the risks. also, in high school, if you don't have sex you are basically telling everyone how inadequate of a person you are. if you're a virgin, it means that you are a loser and less than a person.
i don't see anything "cool" about unscrupulous sex either, especially those that go to sex parties. but, until the young have yet to learn, sex is one of those things that they seem to want to experience