Hipsters, like many other subcultures before them are ultimately a type of conformist. They might not be conforming with the mainstream, but they are conforming with the rules (even if they are unwritten) of the group that they belong to. Hipsters more than many other groups also seem quick to condemn for not following them "correctly".
Initially, hipsters may have been considered rebels against the system, but like feminists, our exposure to their community has now made them a group which outwardly at least appears to oppose the majority's interests in such a way that they feel superior to others. This behavior is not rebellious, and is in fact snobbish at least.