I think the reason is influence. Older people have accumulated more connections and therefore have more power and influence. Their underlings support them beca

I think the reason is influence. Older people have accumulated more connections and therefore have more power and influence. Their underlings support them because they lose access to a great influencer in case of removal. It's more difficult for young people to rise up when there's very little influence to be had. However, in times of great upheaval young people tend to rise up much faster as the incompetent people at the top get removed.