I'm so dull that when I turn on a light, my IQ goes up..
To answer the question of 'why' there will be some kind of attack, either done by, facilitated by, or allowed to happen by the intelligence services is because a particularly bloody attack is a sure way of getting people to DEMAND more surveillance and control.
No attack = question: "why do we need the FBI/CIA/NSA"
My peas-sized reptilian brain thinks such an event is likely, though not guaranteed.
There are no guarantees.