Keep in mind that if you're a native, or even a more "outgoing" kind of expat, you probably won't see those insular expats at all.

I'm also an expat/immigrant. I met some people who have been living here for 10 years and haven't picked up the language yet. The only reason I know about them is because they heard me speaking another language in a quick phone call and wanted a friend.

Like parent said, nothing wrong with that (plus, I'm not American, so I can't speak about the problems mentioned by the GP post)