It is somewhat practical if there is no opportunity cost, but there is an opportunity cost. Four years of a normal class is nothing. If you devote 4 hours per d

It is somewhat practical if there is no opportunity cost, but there is an opportunity cost. Four years of a normal class is nothing. If you devote 4 hours per day for a decade, sure... but that is a lot of time that could be better used for so many other things. Then, OK, so you learned Mandarin but it turns out you need Hindi. Oops. All that time was wasted because you incorrectly guessed which language (of hundreds) might be useful many years later. Not that it matters of course, because by then you've forgotten the language you learned anyway.