Asking us to place reason on the minds of the perpetrators is unreasonable in itself !
I would be if all of the perpetrators were motivated by some form of Islamic theology. But for the conspiracy theorists to possibly have been correct, there should have been an outside group that knew about it ahead of time that didn't necessarily share their motivations. And there should have been at least one reason to take out both of the towers. That reasoning escapes me. I would suggest to the conspiracy theorists that they should compile a list of businesses and organizations that were based inside the towers. Or maybe they should study where the money flowed as a result of the total demolition of the towers.