About a decade ago, I left a humanities Ph.D. program at Stanford after finishing the coursework, but before starting the dissertation. In my experience, my classmates thought very hard about what they wanted to do with their lives, and were very aware of the career risk involved - if not when they entered the Ph.D. program, certainly by a couple years in. (Hanging out in the graduate lounge with the eighth-year Ph.D. students will do that to you.)

However, most of my classmates were so intensely interested in researching their specialities that they decided the risk was worth taking. After all, it's not like they're particularly suffering during grad school. Grad school in the humanities gives you blissful amounts of time to really geek out in the speciality of your choice, and at top-flight universities, the first few years are free (except for the opportunity cost.) If you get in, your basic expenses and tuition are covered.

Note how we lionize entrepreneurs who intensely pursue a low-probability dream, whether they succeed or fail, while grad students pursuing their own low-probability dream get nothing but scorn. Odd, no? What needs to be changed isn't necessarily grad school, but academic culture - particularly its attitudes towards and adaption to failure. If their community was as understanding of their own failures as ours is of our own, perhaps there wouldn't be such drama about their low rate of success.