I'm not sure what PhD students you're hanging around, but all the ones I know are painfully aware of the fact that we're making terrible career choices. No one expects to get a job as a professor right out of the program, except maybe a few people who hope to get a job at a teaching college. Even those who are going to do a post doc are doing it with full belief that it is unlikely to lead to a tenure-track position. And all of that is at a top 10 CS PhD program.

PhD students generally just love research. We sign up for this because it's what we enjoy doing. Companies try hard to recruit us away, but we stay in spite of that, because why would we want to do anything other than work on the one problem we've always wanted to solve?

Maybe it's different in the humanities, but every STEM PhD student I've ever met has low expectations, with the exception of one-- and she has a first authorship on a Nature paper and is working on a Science submission, so I still think she's pretty well-grounded.