You ask as if it is somehow a huge investment. Category theory is not that hard. It became the language of (almost all) contemporary mathematics. Many mathematicians learn it during the first years of their studies. Its core is very small, and most (if not all) of its usefulness comes from the language itself. In other words, there are almost no theorems in (pure) category theory, but there are many definitions and a great deal of examples. If you know at least some abstract algebra, learning category theory will be quite easy. And this language opens the door to conceptual understanding of many areas of mathematics, logic, functional programming, and some other applied sciences.