Be it functional programming, pattern matching, or prototypal inheritance. Once you’ve learned it, you carry these approaches with you which broadens the problem-solving toolset that you have as a software developer. It also changes the way you see high-quality programming in general.
It’s the same with programming languages. Regardless of how you are going to apply a new programming language in the future, it always gives you a new perspective on programming in general, or on some specific techniques.