Learning languages for which there are lots of jobs might sound attractive, but let me offer a different perspective: it is difficult to shine and become renowned in well-established ecosystems because so many people have so much headstart. Sure you might be able to get a job, but you will also be much easier to replace.

In contrast, new and exciting ecosystems (like Elixir) give you the opportunity to become a big fish in a small pond. There is the risk that the language/framework will never become popular (and maybe even fizzle out) but at least you will enjoy your time with it.