With all efforts to preserve endangered languages, there's an implicit assumption that they should be preserved in the heads of human beings. What value does th

With all efforts to preserve endangered languages, there's an implicit assumption that they should be preserved in the heads of human beings. What value does this language and being able to write it have? I've heard people say "preserves the culture", but is there any concrete value to it? Does it help feed people or entertain people, or anything that English wouldn't do just as well?