I don't think we all need to live in fear, but I don't think we should live oblivious to threats just because things don't blow up more often.
But how do you have so much certainty there are threats? To me, I just can't reconcile this assertion that there are terrorists out there intent on killing us with the fact that they never do, despite it being comically simple to do so.
One might counter with the argument that the cargo plane bombs are an example of the ongoing threat. Perhaps, I will admit this is a possibility. But again, why are essentially all terrorist attacks never successful, when they would be so obviously easy on some of these large, soft targets? Perhaps these interceptions are something else? Impossible of course,
I've never had my house robbed, but I still lock the doors and have an alarm system. No one on my street has been robbed, but I can't just assume this street won't ever get burgled because I know that it does happen. So, I'm careful to lock up, but I'm not so scared I have inch bars on the windows, a guard dog, a watchman on guard, etc. There is just enough of a deterrent that it is a hassle for someone looking for a quick and easy break-in.
The question is, is our response to the supposed threat of terrorism proper? Your response to your threat is essentially cost free (except for the alarm I guess). The cost of the west's response to one terrorist attack is anything but free, it is measured in the Billions or Trillions, depending on how you look at it, not to mention the decrease in quality of life, lost productivity, etc.
And you are correct in where I am leaning....the timing of "attacks" often seems a bit too convenient, ie: the recent debate in Europe over the level and manner of US airport security measures.
To me, the theory that there are non-insignificant amounts of terrorists intent on attacking us, but these attacks have all (since we have had no successful attacks in the last ~ 10 years) been prevented by the security measures and organizations, is comical. So where does Occam's Razor lead you? :)
>> "...but there are folks trying to kill us (all of us)..."
Either this is not true, or it is true and our enemy is inept. If we had a competent enemy who was trying to kill us, then there would be a lot more of us dead.
Just this last Saturday presented and excellent opportunity to strike terror into the populace in our nation's capital. John Stewart's "Restoring Sanity and/or Fear" rally saw thousands of people densely packed in what had to have been--judging from the amount of alcohol consumption going on--a very loosely secured area. I've been to other events of similar scale that have been open season on comings and goings. There are opportunities for our enemies to hurt us, hurt us very badly, every day, and they do not take them.
I think this is an important issue to point out because fear of a bogeyman is still fear. Richard Nixon said, "People react to fear, not love--they don't teach that in Sunday School, but it's true." Rahm Emmanuel said, "You never let a serious crisis go to waste. And what I mean by that it's an opportunity to do things you think you could not do before." Bill Clinton identified the soccer-moms as the most important demographic in America, and he was right: they way to vast policy change is to connect it to a threat to a soccer-mom's babies.
There has been a resurgence in fascist and totalitarian ideology within Western government, all based around a hyped-up version of a nebulous, nefarious "them". We continue to play this security theater because it serves a purpose. The classic answer is that security theater instills confidence in the system. But I think it goes deeper. I think it gives the people a target, something to hate, something we can all agree sucks, and then see the futility of trying to change it. It's an indoctrination system to make "us" accept that the "right" way is a militaristic way.