I don't know about you, but sometimes I do things just because I want to.
I think the reason should/could be abstraction. If you find yourself doing kind of the same thing over and over but don't see how you could extract the repetative part in a scalable way in a language with less type support then there may be a good use case for Haskell there.
Learning things is how you keep your brain sharp.
I need to get halfway fluent in JS first, but good point.
Once you get there I recommend then learning Typescript (Javascript with types) and compare the experience with Javascript.