If you are starting your own company or a side project choose a language that a) best suites your needs and b) you know. Unless your goal is to learn a new language you probably don't want to write your business logic in a completely new language just because it's popular at the moment. And outside of stuff you actually have a say in (i.e. stuff you do for your employer) it doesn't matter what language(s) you know as long as you know something that's applicable.
I learned PHP as my first language (well, I wrote some VB stuff for school before that, but I never wrote it on my spare time), after that I went on to JS just before college and in college I learned C#/Java, but also for my web side projects (which I made some money from) I learned Ruby. Now since graduating I've also dabbled in Python and very lately little in Perl6 (just because the syntax looks so nice), but for my actual job I'm mostly working with Python. It's not my favorite language, but my Ruby and JS (as well as general programming knowledge) carries me through the tasks, it's not like I'm in completely different world where I can't function.
My point is as long as you know how to program the language shouldn't matter, obviously jumping from something like Python to C++ is a bigger change than going from Ruby to Python, but it's not imposible and if your employer really just cares about your languages they are either super specialized and doing some weird shit (which might be your thing and then all you can do is to learn that language) or they really don't know what they want/need.