As the character was depicted in the movie (not canon, I know) she would not have hung out with anyone not in her own special little circle before being Called, but she gradually came to see just how shallow and air headed they were ("The ozone layer? Oh, yeah, we have to get rid of that") but her association with, primarily, Merrick, her first Watcher, gradually brought her to the realization that being part of the "in" crowd wasn't necessarily the great character reference that she had thought it was. The girl who only wanted to "graduate, visit Europe, marry Christian Slater, and die" before she was Called evolved gradually into the Buffy that we first saw in "Welcome To The Hellmouth, whose wish at that time might have been to, "graduate, meet (whoever you prefer to name) and STAY ALIVE," at least for as long as possible. Surrounding herself with shallow friends would no longer have been a priority.