It's like a mix of Yuppie, emo, hippy, indie and beatnik which all share that smug liberal elitist attitude. Hipsters just tend to have a slightly better fashion sense imo. A 90's nostalgia thing of mine I guess.
The association with progressive politics can be seen in their inflated ego and low self-esteem as their suppressed social and tribal instincts are manifested in what they think is a nonchalant manner but is actually seen by outsiders for what it is.
That hipster stole my bi-cycle glove!