The Alt Right are suffering cognitive dissonance on this. Instead of apprehending the perpetrators they're blaming Muslim immigrants for the downfall of the U.S., which is odd because being cowards, like the well meaning but even easier to manipulate hypocritical SJWs, they have one thing in common. They prefer not to discus the seminal event that was initiated and framed chronologically and geographically as Ground Zero to implement infinite war in the Middle East on innocent Muslims.
One of the frequent responses to conspiracy analysis is that nobody could keep such a large operation secret.
Well it's not.
It's common knowledge by people who take an interest in reality.