I don’t know if it was that big of a blunder. Iraq for the most part is at peace and Sadam was a big problem. I also remember we got Lybia to give up there nuclear technology which was well advanced. I think I would define blunder as actually losing.
Bush’s invasion of Iraq destabilized the entire middle east. 15+ years later and we are still fighting there. Taking out Saddam also led to the rise of radical Islam (ISIS) and millions of refugees invading Europe. I’d call that a huge blunder. Oh, and as a bonus we got Obama too. All because W had it in for Saddam after Saddam tried to assassinate daddy Bush.