They are teaching, scholarship, and family. Deans have had both personal and professional lives before becoming deans. Professionally, those lives l turned upon teaching well and writing meaningful scholarship. Neither is a skill that can be once learned and retained forever, like riding a bicycle. Teaching requires careful preparation, even when a course has been taught many times before, and the best teachers keep up with both the methods and the substance in their courses through painstaking effort every day.
Writing is harder still.
That is a huge time commitment, and the dean will often be reminded how much time is required by seeing his or her colleagues in action. Most deans, of course, at some point surrender the struggle to remain scholars, and many give up on teaching as well, but that also poses risks, one of which is the increasing distance between the daily experience of the faculty and the dean. An even greater priority for most deans is their families. An academic life is in many ways a blessing to families, because faculty members often have blocks of unscheduled time, including summers and semester breaks, when the pace of work relents and there are more opportunities for sustained attention to children, spouse, or partners. Not so for deans.