He does it because he is biased towards something he has already spent years on his PhD candidacy and many hours on writing libraries already. If he completes h

He does it because he is biased towards something he has already spent years on his PhD candidacy and many hours on writing libraries already. If he completes his PhD, it is likely that he will try to get a Haskell job. Just because he wrote a thousand Haskell packages doesn't mean he is as suitable in another language. Sure he could probably be a C programmer, but his pay grade won't be as high as if he landed a Haskell job to take advantage of his experience and degree. That you cannot see this is because you also have the same bias as Dons.