It's just not that useful. It's only useful in China and foreigners can't really conduct business there. It's basically only useful if you move to China which is just a handful of people and shrinking at this point.
Going by [this list](https://en.wikipedia.org/wiki/List_of_languages_by_total_num...), you can see how if you want to expand your reach, some languages make more sense to learn than others.