But they don't look at the other side of the coin: what happens when a politician comes to view himself or herself as "indispensable" and doesn't bother preparing the next generation for leadership? Is there something to be said for getting out of the way while you're still more or less effective -- before you cause problems?
Of course, but ego-driven politicians, just like ego-driven athletes, hate to put themselves out of the spotlight, no matter the price.