Lies, damn lies, and statistics
Grad students are generally less likely to want to continue in research careers as they go along; less than half of grad students are happy with their stipend; and European grad students are happier than US grad students: nature survey of 5000 grad students
For fun, you can also download the data tables.
In other news, something I figured out the hard way:
although it is relatively easy for universities to hire people with interdisciplinary backgrounds for postdocs, it is much harder to get interdisciplinary faculty positions. That could lead scientists without a history of close affiliation with an established department to serial fellowships and postdoc limbo, or job-hunting challenges in the broader market