An old horse loves its stable; used to describe an elderly person who is reluctant to leave a position of power or relinquish their post.

literally a worn-out horse is reluctant to leave its stable; used to describe a mediocre person who clings to their office or position out of fear of losing their livelihood

Literally "a worn-out horse is reluctant to leave its stable and fodder"; used to describe a mediocre person who is unwilling to leave a comfortable job or high position despite their lack of ability.