I don't think that many people learning those interesting-but-not-immediately-practical languages do it to appear cool (what I think is the defining characteristic of hipsters.)

Programming characteristics are quite different from fashion/lifestyle. It takes much more effort to learn a language than to choose an obscure band to listen to. And the payoff in perceived coolness is also much smaller - see for example http://steve-yegge.blogspot.com/2010/12/haskell-researchers-...