Great topic Min!
To me it's always been the three P's. Power. Position. Prominence.
As has been noted, people are complicated. Many elders are warm, even sincere in their desire to be a force for good. But in the end it's the three P's that keep them motivated. Ask yourself, why is there so much angst surrounding those that half to "step down?" It's not because there is a shortage of people wanting to fill their shoes. There will never be any vacuum when it comes to people "reaching out."
The angst comes from a loss of the three P's. And what will people think? It's also very interesting that most that quit being elders are not re-appointed.