After the U.S. toppled Saddam Hussein in 2003, some even dared to dream that the country would become as rich as Gulf States like Kuwait. There was no Iraqi government in place for a long time and, for several months, life in Baghdad was free of bombings and attacks.
To make things worse, the U.S. dissolved the Iraqi army and started a process to remove those politically aligned with Saddam, which ended up taking jobs away from thousands of Sunnis and seemed like an unfair witch hunt. Add to these political actions poverty and a lack of basic services, and you end up with a deep, sectarian divide in Iraq that I believe led to the insurgency and the problems that exist today.
I despised Saddam, but I don’t think an extremist group like the Islamic State would exist under his rule. Even if Saddam had gone crazy and killed a bunch of people, it wouldn’t be anywhere near the number who have died since he was overthrown. I see a civil war coming, and an Iraq divided into states.