What about the people that study klingon? Or Esperanto? Or Elvish?
You assume that a person cannot gain something by simply learning something that has no practical purpose. This isn't the case. By working on BF, someone might make some neuron connections that help them with logical thought with other projects, by breaking down logical thinking into very simplistic, basic symbols--completely removing "language" out of the equation.
You just don't know. :P