I do a LOT of international business and change jobs frequently. I have worked for French, English, German, Austrian, Japanese, Korean, and Italian companies.
I don't know anything about doing business in China, which may be a special case, but in my experience it is less and less important to speak a foreign language in business. EVERYBODY who is ANYBODY in today's world speaks English. Some countries have a culture that resists it (e.g., France) but as a general proposition, you can get by just about anywhere speaking only English.
And not to be discouraging, in order to master a foreign language well enough to conduct business discussions in that language, I'm convinced you have to go there and live for at least six months.
So for most people, it is more profitable to spend your learning time on substantive subjects, rather than spending all of the time it would take to master a foreign language. It just isn't worth the effort. Sophisticated foreign countries start teaching their kids other languages in early primary school, when it is easiest to pick up a new language. If you are thinking about it as an adult, forget about it unless it is absolutely imperative.