He has a family that he has dragged around the country the last 20 years. He has made a ton of money. He just got fired. He's extremely high strung and likely his body and mind could use a break. I remember the evaluations Buzz got done on his body and the results he shared that the stress of the job was taking on him.
Maybe Crean is different, but coaching at Indiana and their whack job fans likely takes years off your life. It's not like he was coaching at Mount St. Marys.