There is a great tradition in academia. If you are a successful academic you are supposed to have PhD students and guide them in their dissertation research. The more PhD students you have the better. It is a great responsibility because you have to make sure that the PhD student finishes his/her PhD degree in a reasonable amount of time. In modern times the PhD advisor has additional responsibilities such as helping the student find a job. Supervising PhD research requires leadership and coaching skills. It takes patience. It involves pure giving. You freely offer your time and energy.
Einstein did not have any PhD students. This shows a selfish side. He is still my hero but I often thought about this and questioned his selfishness in this regard.
In Wikipedia there is a section that lists his “notable students” but none of them were his official PhD students. He had assistants but they were not PhD students. Those “assistants” were professional physicists with PhD degrees.