Bush announced a crusade, included Iran, (who had their own concerns about the Taliban, their diplomats had been murdered by the Taliban,) in his "axis of evil" speech, and invaded a Moslem country that had nothing to do with 9/11, thus proving Al Qaida right.
Now we're living with the consequences.
NB, in the same way that the House of Commons could not have been compromised due to adequate security, European airports could not have suffered a 9/11 type attack. Bush had been warned of the threat of Al Qaida by the departing Clinton administration, he chose to ignore that warning, and 9/11 was the result. Spoiling the ship for a ha'porth of tar, and all that.
His actions post 9/11 alienated all Moslems and galvanised a generation of disaffected young men. And now we're all living with the consequences of what is clearly the most disastrous presidency of all time. His legacy, his mess, and it will take a least a generation to clean it up if not longer.