I am not disagreeing with you, and I use the functional aspects of Python a fair bit. As I said I don't think learning new languages is a bad thing. But I do see some devs that collect languages / frameworks like football stickers. If you are learning a new one every second month you won't have much depth to your knowledge in any of them.
Python does support functional programming, but it's not a primary way of doing things. By learning one of the Lisp-like languages you can better understand all the idioms you would use in Python to apply functional programming concepts better.
You don't need to necessarily add it to you projects at work, it can be as simple as doing an online course.