throwaway92938
There is an opportunity cost and there are plenty of motivated developers that instead of learning yet another niche language decide to work on algorithms, applications and generally more difficult problems. Few languages offer enough advantages to overcome the fact that the latter is almost always a far better use of your time. As someone that knows Clojure relatively well, I'd argue that it's certainly not one of those few languages. Also, the trade off continuously gets worse as the popular languages adopt the good ideas from the niche languages and as problems continue to get more difficult and rely on teams of developers with library support in a wide variety of domains.
HN seems to blindly accept the idea that developers using niche languages are good but I certainly haven't seen any proof of that and I haven't seen anything to even remotely suggest that good developers gravitate towards Clojure.
Great developers have to be working on hard problems and almost all of the hard problems in our industry, outside of language/chip design and correctness proofs, are being worked on in relatively boring languages (C, C++, Java etc.). Most of the niche language users I've met are working on basic CRUD web applications.