Staff retire for all kinds of reasons. Sometimes, it's because they no longer wish to play on Famcraft (they got bored, their computer is broken, they have to focus on school, etc) So they quit to make room for a new person to take their place
Other times, people retire to make time for themselves to play!
Being staff can be really hectic and time-consuming, because you're asked to drop whatever you're doing (building, farming, etc) and go help someone, be it giving a tour to a new player, or inspecting a grief, doing a world-edit, etc.
Sometimes, you don't get a lot of time to actually play or build, because you're constantly helping people (admins especially are extremely busy as soon as they log on, because they have so many responsibilities that only admins can do like spawners, stargates, and etc) So many times, staff will decide that they've helped out enough, and step down so that someone else can move up in rank, and they can spend their time playing, building, and enjoying themselves.
It can get overwhelming sometimes! lol
