Hipsters are simply another youth subculture movement that differs only aesthetically from all the previous subculture movements we've had in the past i.e. Punks, hippies, goths, beatniks and so on. All these movements have been very different both in what they produced and it the values espoused but the fundemental is always the same, it's about avoiding the mainstream.
Now people have pointyed out that in rejecting the mainstream they conform far more with each other than than "mainstream" people do. However while true I think this misses the basic purpose. It's not about some sort Nietzschean indivdualism so much as a rejection of what they see as the values society wants to impose upon them.
What I find interesting is that the term hipster was used in the 50's/60's to refer to the beat generation, and the similarities between the groups are fairly obvious (although under this view Bryan Lee O'Malley is this generations Jack Kerouac, which I feel speaks very poorly of this generation to be honest).
As to why people are saying they've never seen one, well that's because it's not a fucking club, there's no offcial membership and there isn't even a particularly tight definition. A subculture will always be very varied and most people who could be defined as hipsters will not fit a broad sterotype.
