For good or ill, three is in fact a market for senior academic administrators, as there is for star researchers and, of course, star athletes.  Salaries are set, more or less, by a global market.  Are they reasonable? Hard to say. As noted in some comments, administrative leave is in lieu of sabbaticals foregone and is intended to provide an opportunity for administrators to catch up in their academic fields so that they can return to teaching and research.  Ideally, universities are less hierarchical than other organizations and presidents do return to the lab and the classroom.  One hopes so.  We would want top people to take on these leadership roles without giving up their research and teaching careers.