It’s at the bottom of the ocean for sure. I think he called the tower and said that he would crash the plane unless certain demands were not met regarding the release of his buddy that went to prison the day before. They didn’t comply so he crashed it. http://shanghaiist.com/2014/03/17/links-between-mh370-disappearance-zaharie-politics-dismissed.php
That seems like a very probable scenario.
He wasn't and isn't in jail -- so there would be no reason to make the demand.