This is not my assumption. The holistic or qualitative benefits of learning a foreign language are apparent. To state so is trivial. I probably disagree that a majority of Anglophones learn a foreign language due to a culture which it pervades. I almost certainly disagree that people are learning a language for its own sake. I state specifically that it is an attractive view to hold, for the reasons mentioned. People do not want to appear "shallow", in whichever subjective fashion they imbue onto others. It is attractive to say that you're learning due to an innate curiosity; even to say so without acquiring a language. Many people use social media for this purpose, explicitly, and it appears to be a common topic of discussion here; "fake polygots", et cetera.