I always have my doubts about hot-news social science research ("Being liberal extends your life!"), but this research below seems solidly based in math (econ) and matches the impression I've had after some 64 years of inhabiting various college and university campuses and hanging at numerous coffee pots to hear the gossip. So for what it's worth:
The Postsecondary Education & Economics Research Center at American University, using research from the Yale Tobin Center for Economic Policy "found that graduate degrees in medicine, law and pharmacy generally have the highest return on investment. By contrast, degrees in popular fields such as social work, psychology, and curriculum and instruction may actually have a zero to negative return after factoring in the full cost." (WashPost)
Yikes.