Does anyone know where B, D language, Haskell, Scala, COBOL, Fortran and other unfamous languages are used? I know that Scala and Haskell are functional programming language but I don't know where it is useful and COBOL was used in US army but I never hear about them.

Cobol is still in use in old bank systems that are too ingrained to be completely replaced, Fortran is all over the world of physics, the others are still new really, functional languages tend to get used in high-volume data processing and compiler construction these days. They all have a place though, you just need to think about the strengths of a language and the applications fall out naturally.

So COBOL is gonna die. And why Fortran in Physics domain?

I know of people who still use Cobol and value it as a skill, it's not going anywhere any time soon. Fortran in physics because there's a metric tonne of legacy simulations in it.