> how would you feel if she were a math professor instead? Being an academic mathematician is just as self-indulgent as anything in the humanities.

The academic mathematician who wants to make more money can probably get a job in industry, or learn an in-demand skill such as programming, stats, etc. An assistant professor of Native American studies probably doesn't have the same capacity (to put it bluntly: is not as smart), so it was a much bigger gamble for her to take on so much debt to become a professor.