Saddam became too unpredictable. He sealed his fate when he launched missiles at Tel Aviv in the first Gulf War. For some reason, people seem to forget or gloss that over.
The Israelis had attacked Iraq in 1981 and Iraq and Israel never signed an armistace in 1948. Technically they remained at war.
He was quite predictable. He understood Israel as a liability to U.S. policies in the region and sought to draw Israel into the conflict and split the U.S. coalition against him.
Nothing crazy or unpredictable there. A simple, logical, strategic calculation.