Check out this link for a quick summary of the misperceptions Saddam Hussein had piled up that made his decision-making in 2002-03 understandable.
He thought that Desert Storm was a victory since he didn't lose power. Plus he received information from his subordinates that minimized the losses and maximized the successes--wildly so. This put him in a position to think that the US was a paper tiger, so wishful thinking turned out to be a disease on both sides in 2003.
Jervis made clear long ago that misperception is rife and can cause heaps of conflict. And 2003 has proven him right yet again.