Power is very habit-forming. It has its own peculiar high, which makes it very difficult to let go.

It is likely the biggest reason for term limits.

There is no doubt in my mind that FDR was controlled by it.

Though it is wrong to seek power for selfish reasons, the more power one has, the more they will want and the less willing they are to relinquish it. Consider the former Senate Minority Leader McConnell. Even with one foot in the grave, he hangs onto his power tenaciously, though it will soon cease to be of any use to him.