Irak war seemed to me reasonably "in plain sight". And there were other blunders as well. What I find amazing though is that more people passionately believe very strange reasons.

30 years ago people were like "meh, sure we don't get something, I bet there are hidden interest that I don't know about". Nowadays they are like "oh, yeah we attack country X because they have aliens that attack us telepathically, I know that for sure and if you don't agree you are an alien too!".