Iove the ideas behind functional programming but I never properly learned a functional programming language. I will probably never have the opportunity to use it professionaly and learning it just for hobby doesn't make sense to me.
If I am developing something in my spare time I also like to use something I can earn money with so I can hone and maintain my earning skills. Maybe sounds like min maxing.
If I would be in a situation where I can develop software just out of pleasure or pure curiosity, I would use just whatever language I deem interesting.