As an advisor, you can pursue your research interests and expand the boundaries of knowledge by having orhers help you. You ca co-author new findings and serve your profession by developing future scholars.
It is my passion to conduct research. By guiding some students I become a researcher and mentally travel with him or her. In this process my knowledge is enhanced. With my students my publication increases.Any way some times such publications may not benefit you if you are too senior. Presence in the lab, discussions in Research Promotion Committee, drafting thesis are the area I like.
There are no specific reason to guide. I feel honored to see respect from the research scholars.
You learn a lot while you are guiding a thesis. In some institutions in countries like South Africa, besides adding to your CV you actually get paid for every masters and PhD that you guideyou
To achieve communication and scientific passion, and support young researchers, and to have a place even if it is small in the field of your scientific specialization.