It does feel more like a falling out with the companies higher up management and maybe they have other personal issues too, so they just decided it was enough and it was the right time to close that chapter of there life. If someone makes $100 million I think for some it is more than enough to consider it enough to take a step back and go and enjoy life. Using the whole idea of they could have stay for more comes from the idea of greed, but perhaps for a religious man they are contempt when they have enough.