Not exactly on Iraq. Iraq was ruled by the minority Sunni religious/ethnic group under Saddam (approx. 35% of the population) and the Shia majority (approx. 65%) were largely discriminated against. You are right, W and his Neo-cons didn't seem to understand this ethno/religious split and pushed for a "democratic" government, seemingly oblivious to the fact that a majority rule government would just shift power to the larger Shia demographic and set the conditions for a civil war..

The Iraqis didn't have to fight a civil war however, and though there was always violence targeted at U.S. forces the main fight was between these groups with the U.S. stuck trying to tamp down conflict, an impossibility once both sides had ramped up violence and atrocities against each other.

Tragically the Bush stumbling and incompetence has inflamed this basic conflict throughout the region with deadly consequences in Syria, where a protest movement quickly devolved into Sunni/Shia war, in Afghanistan where the minority Shia Hazaras have long been subjugated and where Sunni Taliban have taken control and now in Yemen where the same battle is being fought. Even more sadly the U.S., with trump playing the useful idiot, has strongly sided with Sunni Saudi Arabia, from where the most virulent forms of Islamic extremism have sprung (Wahhabist movement that spawned al Qaeda, ISIS, Boko Haram, AQI among others)... dangerous alliance, given that Iran is the de-facto protector of Shia populations in the region and far too powerful to just disappear, and "honored" by U.S. presidents and government because of our dependence on oil.