The idea that young people actually choose graduate school in the humanities as a math-avoidance life strategy is absurd, as is the idea that they are motivated primarily by salary.
I agree; PhD students have always been successful students, and it’s puzzling and psychologically painful to reach the top of the educational ladder only to have the trapdoor to the sky nailed shut.
PS if you are a good enough student get into a funded PhD program in the humanities, you are probably reasonably proficient at math compared to the general population, at least enough to be a finance major if not an engineer. You just have chosen not to be. Recently there seems to be a number of individuals on CC who seemingly cannot understand why people might choose an occupation that is not quant-based unless they are stupid, a view that I find, well, stupid.