My biggest beef with Bush over Iraq is not the invasion. I served over there and I have always been convinced we were going to have to take on Hussein again, sooner or later. Not a lot of people know or remember that Hussein made another rush at Kuwait in 1994. But we were there to stop him that time.
Bush made an extremely flimsy case for invading Iraq, but we had been winding the military down for a long time by that point. The "peace dividend" after the collapse of the USSR. Our readiness was seriously eroded. If we had waited on Hussein's timetable, we would not have been as prepared to take him on again. As it was, our equipment was barely up to the task.
No, my problem with Bush was his follow-through. He totally fucked it up by demobilizing the Iraqi army. After WWII, we kept the German and Japanese forces active until those countries could get back on their feet on solid ground.
It was the demobilization which cost the lives of thousands of US troops.