It means that if there was a 9/11 every week, an average American in America would still be more likely to get run down crossing the road, killed in a car crash, or murdered, than die from terrorism.
You can't be stupid, but you can't run around like chicken little all day either. Que sera sera...just watch out for of those people at a sale. They run you over in a heartbeat just to get to the 50% off table.
The threat of terrorism all over the world is real. No one with a semblance of knowledge of world events can deny this fact, and that and it can hit you anywhere at anytime. Just ask those families whose next of kin were killed in 9/11 or the London bombings, or the thousands massacred by terrorists in India, Africa, or close to my home, the hundreds murdered in Bali. Modern technology, associated with outdated, anachronistic ideas (often steeped in religious concepts), makes terrorism an every day possiblity. But afraid no (unless, maybe, if you live in certain parts of India) but aware - yes.
In my opinion, we may be becoming the evil communist empire we fought and won a cold war with; simply because our elected representatives can't tell the difference between the common offense and the common defense.