Even if your goal is solely to prevent terrorist attacks and you don't give a damn about domestic collateral, it is still not so obvious. The question is whether, with all the data in the world, there are signals in that data that are exclusively correlated with terrorists and terrorist activities. And, secondarily, whether data mining and ML techniques have found, or can in the near future find, those signals. If not, then, in Schneier's words:
"Piling more data onto the mix makes it harder, not easier. The best way to think of it is a needle-in-a-haystack problem; the last thing you want to do is increase the amount of hay you have to search through." [1]
[1] http://www.cnn.com/2013/05/02/opinion/schneier-boston-bombin...
We--by which I assume you mean the United States--are at war with whatever seems to be most profitable to the powers-that-be at the time, whether that is drugs, Muslims, or our own citizens. There is a very valid concern that such a policy of scaremongering and sly abuse of power could result in Bad Things (tm) if the beast decides that a war on one of us would be a worthwhile expenditure of time.
To pretend otherwise is foolish.
There are people out there that wish us harm, as there always have been. Part of the burden of doing great things is the acceptance of the fact that you'll be targeted by those less capable--and part of the requirement is that you bull ahead and don't let it bother you.
This is a good example of a knucklehead comment. There is no profit in fighting cave dwelling extremists who want to make sure girls don't go to school. Instead of wishing for the demise of the US you should be saying thank Christ the Americans are in charge. HN can be a bag full of stupid on non-technical issues. I am going to start actively campaigning for the US to stop paying for the EU's defense.
Unless you are making bullets, guns, body armor, etc. Never underestimate the US government's ability to do seemingly pointless things just to prop up certain businesses. We see that very same pattern of behavior elsewhere in the government; what makes you think the military is exempt?
You did not have to go and prove the point so extensively.
But anyway I have found that data based decisions and policies tend to produce better outcomes than emotional based ones.
I do find my theory sound - that currently in the world there is no terrorist organization (or even state actor outside of Russia/China) that is capable to deliver enough pain to convert the US to failed state.
The Russians were hammered terribly in WWI and WWII and survived - 20-40 million lives lost. Germany was razed and survived. Poland was decimated and survived. Japan got direct nuclear hits and survived as a state. Israel is under constant real treat for a tiny country and is doing fine.
9/11 was a black swan - a lot of systems already in place failed. The subsequent plots were all incompetent and much smaller in scale (which we are thankful for).
So the statehood of the US is in no danger. And there is tiny danger for the civil populace.
There may be a lot of factors that could turn the US into the Mad Max world - economic collapse, ecologic one, meteorites, IP laws gone berserk.
But the idea that terrorist could cause the fall of the US don't hold to basic napkin math.