Knowing a common second language is almost never useless. If you play mmorpgs, you have probably seen people talk in spanish, portugiese, chinese or even german. If you work in the restaurant business, you might have to learn the language of the nation the recipes came from , say korean or taiwanese, is a good example. Only in the us, are we required to learn the language of people coming to our country. Almost everywhere else, you need to learn their language or your sol. So if you want to travel outside of places that speak your native tongue, you need to their their language at least semi fluently. Don't want to go to france and order a potted plant XD