what better time to leave than when you are on top and have orchestrated a remarkable turn-around. Her services will never be in higher demand than they are now.
Yes, leave now and get a substantially higher compensation elsewhere is a purely rational thing to do. Although people do not always do purely rational things.
I just wanted to note, that what happened at AMD recently is a team work with many contributing people, some of those key contributors may be people we have never heard about. So I would be a little bit cautios with statements like that "she orchestrated remarkable turnaround". The same (or even better) thing could have happened with a different CEO.