Why do research faculty pursue administrative positions, such as dean, provost, president, etc. ? Do such positions spell the end of one's research? At a recent seminar talk, I was amazed to note that one of the two coauthors (not the presenter) was the president of a large and well-known university, since I had always assumed that taking on such a position would necessarily mean the end of a research career. 


Are there m/any examples of people that continue to do substantial amounts of research when in a senior administrative position, such as dean, provost, president, etc.? 
Do research faculty often become deans, presidents, etc.? Why do faculty usually do this? (I understand that there might be a pay increase, but does it usually indicate that they no longer want to do research as intensely?)
In these positions, one gets to influence the direction of the whole university, rather than the direction of the research of 1 to n individuals. At such magnitude, one can effect more change. 

Often people get disgruntled with the way things are run at the level they are currently working. The only way to fix things is to move to more managerial positions. Don't like the way the Masters program is run? Become Coordinator of the Masters Programme. Don't like the way the faculty is being run? Become Dean.