mfrank summed it up pretty well (even if I don't know what interminable means). His point was this ... Billy Donovan came to the right decision in returning to Florida. The narcotic like euphoria of being offered a ticket to the next level wore off. The deal he got at Florida was pretty sweet. He could never win another NCAA title again and he is set for life in the college ranks. He is king of the hill. Why trade that in for the possibility of becoming the latest college head coach to be embarrassed in the NBA. Why trade that in for the headache of the NBA grind.
They answer of course is that the next level offers more fame ... more fortune ... immortality. If you have the stones for it.
I guess Billy didn't have the stones. Which is okay if you know you don't have them.