I'm a mathematics college lecturer and have an mphil degree in the subject. But I often wonder why I'm learning this senior undergrad level mathematics---analysis, topology, functional analysis, abstract algebra etc. Whatever I learn from my mathematics books is hardly any use to me when I move around in society where I live.
The only use I'm presently making of my mathematics knowledge is to teach this subject to my pupils (those amongst who major in mathematics are likely going to teach it in turn to their pupils). I know that engineers study and utilise mathematics, but the only things they ever get to learn during their degrees are the calculus, linear algebra, differential equations, numerical analysis, and statistics / probability---all at a rather elementary, calculational level. And I also know that computer science students also learn discrete mathematics.
But those who are studying mathematics here are only learning it to get through their degrees and to later teach the subject, most often at secondary school and elementary college level, at schools, colleges, universities, privately run tuition centers, or by going from door to door tutoring.
Apart from this, I find that abstract mathematics has little use at least in my daily life; nor does it get discussed or talked about, unlike literature, politics, economics, etc.
Once on my return home while I was pursuing my mphil, an elderly kinsman, who has had very little schooling himself, inquired of me what I was learning at the university and requested me to teach him some of it too. Now I was really confused how I should communicate to him (a man who doesn't even know the high school mathematics) concepts like the Hahn Banach Theorem! So I was speechless and he a bit disappointed.
During my interaction with my parents, siblings (one of whom is a civil engineer studying for a PhD at Univ. of Queensland and another is a dentist), or other kinsmen, whatever little bit of mathematics I've learnt doesn't seem to do me any good (apart from the salary I earn of course, but even there it's often too much of a struggle for me to teach mathematics with my poor eyesight).
I wonder if it's like this with most (if not all) of the SE community.