Abdicate, it's a word that we don't hear very often. And that's because, in the annuals of history, it's a very rare occurrence.
The reason for this is simple, Kings make enemies. It's the nature of wielding power. And if a King should decide to step down, those same enemies are likely to do him harm.
Staying in power is a matter of basic survival. To do otherwise would mean physical harm and possible death.