Definitely not a must. As always, it depends on what you want to do. If you want to program micro processors, you could do that with JS, but you are better off with a system language, like C or Rust. If you go into the industry and do I4.0 development, it's quite likely you will need ABAP (though SAP also uses JS for certain front-end stuff, like UI5, these days). Let's take number-crunching algorithms and machine learning. Forget about JS, you will have to go for a language which is actually good at processing.
JS is awesome when used for what it was intended for: UI and user interaction. It is great for IO and asynchronous tasks, but it will always fail when you need the power to calculate stuff. That's also the exact reason why we will get WebAssembly, which could introduce new features allowing us to create powerful number-crunchers for the web (for example a physics engine for a web game). WebAssembly, however, will not be written in JS. People will use Rust, C/C++ and other languages.
So should you learn JS? Probably, since it is a very universal language perfect for human interaction. Is it a must? No, in no way! Always use the best tool for the job!