hipster paradox
n. The tendency for people who assert their individuality using deliberately anti-mainstream dress and grooming to end up all looking very similar, thus becoming the new mainstream.
Bearded hipsters, with fix gear bicycles and hand-knitted beanies, seem to be everywhere.

While they may strive for individuality, they have instead been caught up in one of the greatest mysteries of our time; the hipster paradox.
—Ellie Zolfagharifard & Victoria Woollaston, “Why all hipsters look the SAME: Scientists reveal the maths behind beards, bicycles and man buns,” Daily Mail, March 10, 2015
The hipster culture is the first subculture not to acknowledge its own existence. No self-respecting hipster will ever admit to being a hipster. This appears to be the first and most important rule of being a hipster. Hipsters won’t conform to people and products of mass culture while simultaneously sharing the same views with others within their 'subculture'. They conform in their non-conformity. This so-called hipster paradox has been heavily criticized by non-members.
—Keesje Heldoorn, “Beyond hipster: The meaning of style in an elusive subculture,” Project Y, November 02, 2014
For a culture that prides itself in being the persistent antithesis of the conventional, the disparity is appalling. Such is the hipster paradox — from an exclusive few who have managed to convincingly set a certain standard that makes them different, albeit pleasantly, hipsterism has grown into such a widespread, often misinterpreted, movement that being antimainstream has become the mainstream.
—Blessilde Limoso, “The hipster revolution,” The Inquirer, October 28, 2013
2010 (earliest)
But in accordance to Albert Einstein's Hipster Paradox, if you have a million people turning towards the unconventional, then you create a separate majority of conventional Hispters [sic], which is exactly what is happening today.
—BTL, “The Hipster vs. The Frat Guy,” The Twinkie Life, September 29, 2010
I exist in tandem with a lot of hipsters. I cannot myself claim the term, because of the hipster paradox: all hipsters want everyone to think that they are hipsters, but no hipster can ever claim the identity openly.
—Rachel McCarthy James, “American Apparel: Abercrombie & Fitch for hipsters,” Deeply Problematic, July 27, 2009