Why major in English as a foreign language, if you're not going to be a language teacher?

The English major on its own is insufficient for many jobs other than English teacher. Also, many other majors graduate with a decent amount of English. However, you are not wasting your time doing English. I can tell you that 10% of my students studying English majors already have majored in other subjects and are studying an English major as a second degree as it is a statement of a high proficiency that can differentiate them in a crowded job market. Having both and English major and some other specialization is the double-edged sword that will lead to a successful career.

You don't actually need to have perfect English for many professional functions. Translators typically work translating from the foreign into their own native language. Think about it. If I want a document translated into Japanese, am I going to hire an English man with a Japanese major or a Japanese man with an English major? To translate into Japanese, I hire the Japanese native. Whereas, to translate from Japanese into English, I hire the English native.