One word-——ISLAM >>> wolves at large with Saudi controllers & $
It's doesn't explain why we get so few incidents relative to the large numbers of Muslims we have here (about 3m people, not counting tourists). There are plenty of Muslims who don't agree with our invasion of Iraq and Afghanistan. For some, it's a religious matter, whereas for others, it's purely tribal, in the sense that a Christian or lapsed Christian might get worked up upon hearing Christians are being persecuted somewhere in the world. A Christian or even Christian turned atheist doesn't have be devout to automatically identify with persecuted Christians - the reflex is to think "that could have been me".
Point being that millions of Muslims stateside think Uncle Sam is beating up on poor Ahmad or some random Muhammad-lover overseas, without also thinking that the solution is to set off bombs to kill large numbers of random American civilians or even to kill anyone here. For these Muslims, their disagreement with our Iraqi and Afghan expeditions goes in the Injustice of The Day Inbox along with lazy welfare spongers and punitive Federal regulations.