Thank God these people are generally idiots. I hasten to recall how Mohammad Atta, in his defining moment, came within minutes of missing his flight... And then there's Moussaoui attempt to learn how to fly planes but not land them...
I would not define them as idiots. Atta murdered nearly 3,000 people and brought down the trade centers. He did not almost miss his flight. He had the timing down perfectly because he had lots of dry runs. He knew how much time he needed to get to his flights while spending as little time as possible in the airport. He also knew that the man in Maine withheld his boarding pass for his Boston connection, when it should have been given to him. They sent up lots of red flags, sure, but idiots, no. People who need to be wiped off the face of the planet? Yes.
These things suggest that Atta & Moussaoui were conflicted, and undermined themselves through avoidable errors.