Currently, the situation in academia is that graduating from a top PhD program is almost a requirement for landing an R1 tenure-track job. However, many of these graduates will not end up at similarly top-ranked schools for their job, and as such are at middle to lower ranked schools.

At these schools, their research is generally still along the lines of what they did in their PhD/postdoc, and PhD students as such follow them, doing this sort of research. But some research fields have little to no industry relevance— a PhD student working in such a field at a middle to lower ranked school would have bleak prospects for academia, and also related industry jobs.

These PhD students as such often have to switch fields to stuff like data science etc. (often through self-learning in online courses) which are unrelated to their original field of research, or end up on a string of postdocs endlessly searching for a job. Many may have been better off getting a job right after undergrad and slowly working their way up.

In such cases, is it immoral to advise these PhD students?