1. The only good reason to get a PhD is that you want to pursue a research and teaching career. Almost surely in academia, sometimes in an appropriate consulting/research institution (Urban Institute, Rand).
2. There are two good reasons to become a professor--you want to do research, you want to teach. If you want to teach, mainly, be sure to find a position at an institution where teaching is a primary value--an undergraduate college, a comprehensive university that is not trying to become a research university, etc. If you don't want to teach, don't go to a university or a college--consulting/research will work better for you.
3. If you don't want to teach, and don't want to do research, why are you doing a PhD. If it is to challenge yourself intellectually, that is fine. If you want to write books, and have a good day job, that is fine, too.

Otherwise, perhaps you ought go to medical school or law school?