If you don't become a politician, what can be gained by studying politics?

The use of the term “politics” rather than “pol. sci” is significant. Much of what was regarded as political studies was political history and philosophy. But, as the Soviet regime so nice pointed out to academics there, if you do not say anything, you cannot be blamed for it. Therefore, “science” meaning statistics and data became the rage. Altho I would say that a century or two of studying every historical pol. event possible etc., leaves little remaining potential original work.
Hence, the rage of behaviorism or pol. statistics, which so far as I know, has been a complete waste of time except for the wage earners in U. depts.
One of the main features of a U. edu. is whether the graduate has learned to analyze data adequately. That might be mathematical, linguistically, chemically, poetically, etc. You can be well educated with serious application in the study of politics. However, the question today is more of how much can you earn from it is real dollar terms. Clearly, the only answer is that we must all become accountants, or beekeepers. Or beekeeping accountants.
One thing I would say; no matter what you study in your 1st two years, do a couple of courses including Plato. The lessons will remain relevant long after you have forgotten Accounting 101.

Political science is the study of human interactions that lead to group activity – anything from sex to making war.

If you want to have sex, or you want to destroy a significant chunk of the planet, understanding politics can help.