I agree with all of the points that peer pressure is an influencing factor. Sometimes as a species we are more sheep-like than human. There is one other factor that hasn't been mentioned yet, and that's the fact that tracks sound completely different when played out at a venue than they do when on your turntable at home.
A tune played to you round at a mate's house, and which you express no real like for, suddenly becomes something completely different when you hear it pumped out loud and bassy at a venue for the first time.
Mind you, numerous times in the past, 45s bought because I'd heard them played at clubs or allnighters have sounded, well, quite disappointing when played in the quiet and comfort of home; so much so that they sound like completely different songs that perhaps I wouldn't have bought had I heard them in a domestic situation first.