Since you make no argument why learning a foreign language is different from anything else, your entire post becomes quite meaningless since it could be applied

Since you make no argument why learning a foreign language is different from anything else, your entire post becomes quite meaningless since it could be applied to literally anything. Math certainly lowers the graduation rate. English literature too. History. Biology. etc. If you want to make a sensible argument, please argue why learning a foreign language is different from learning math, history or whatever else.