Welcome to the forum, lokolan.
I think it is generally difficult to provide any general good advise for something like this, as it really depends very much on which kind of person and developer you are. But I can share part of my story:
Personally, I find it rewarding to try to work with new languages once in a while.
I have changed from professionally using C++ to Java, to C++ again, and I have been working for ~5 years full time with Elixir. Even if I were to go back to work with an object oriented language, I have learned a lot by spending time with a functional language. Of course I would have some catching up to do, before I would be fluent in modern C++ or Java, but I believe it can be done (and still make me a better developer in the end).
I totally agree with k3n, that the programming language is only part of the equation when it comes to career and job satisfaction.
No programming language will ever be perfect. Nor will using a specific programming language replace the need for being a skilled developer. This also goes for Elixir. Some of the code I wrote 5 years ago, which is still in production, is truly a mess and very complicated to understand. Other parts are easy and straightforward.
Like all other languages, there are many ways of structuring and writing Elixir programs. And as your system grows, certain ways of doing things are less optimal than others. Unfortunately, it is not always possible to tell, before you run into to trouble.
This is, as far as I see, just how software development works. There is simply no magic solution that can be applied equally in all cases.
What Elixir brings to the table, is an extensible language, an awesome foundation in terms of the BEAM, a set of really good frameworks and libraries (Phoenix, Ecto, Nerves, Plug, LiveView, Broadway, …) and an awesome community that generally has a very high quality of libraries.
I jumped head first into Elixir 5 years ago, and even though I have had my ups and downs with it (and there are things I dislike in the language), I am generally happy about that choice, and see myself working with it in many years to come.
