Why does everyone think PhDs want or need to go into academia? I never planned to be an academic when I decided to start my PhD. I think that's fairly common.
Probably because, outside of a STEM discipline and a few other exceptions, there isn't a distinct non-academia/teaching career path.
Combine this with both a larger social push for higher education, declining state support for local public institutions that in turn drive a need for higher enrollments to cover costs without (even larger) tuition increases. And add to that a k-12 educational pipeline that has failed in (fully) addressing the need for quality STEM education.
This, of course, oversimplifies the situation to a large degree. But the above factors contribute strongly. Intelligent and driven students, coming into the Higher Ed community with an interest in advanced degrees but relatively weaker STEM backgrounds, are disproportionately represented in humanities & social sciences programs.
