I want to know why some supervisors who are just out there screwing up people? It is because these students may one day be your “rivals” for grants? Is is because you experienced terrible supervision during your Ph.D. that you think you ought to do the same to your own student? Is it because students are just dumb that is is not worth spending your time on them? Then why do you even bother to agree to supervisor them in the first place? Is there a reason of withholding the defence of students? Are students just really there to follow your instructions and order without questioning it? Why do even University administration defend and protect these people because they are tenured?
What joy do you find in ending the dreams of students of becoming a scientist/researcher?
What is it so attractive to you that your own research group becomes ブラック研究室 Black Lab akin to those black company in Japan?