Many people think the costs associated with the war on terror has been too high. There are many ways of getting some clarity on the subject, one of them is measuring the socialeconomic alternative cost of how many lives could be sacrificed which would have the same effect. (Take the numbers below with a pinch of salt, they are not the main point.)
First off, I'll need to establish some type of credible socialeconomic cost of the war. Nobel memorial prize winner Stiglitz has provided an estimate of $3-5 trillion, and to make a point which will come apparent at the end I'll use the lower bound - $3 trillion.
Secondly, I'll have to put a number of how much a life is worth. There are many ways of doing it (ask an actuary), but the results tend to come out in the range of $4-11 million per life depending on the methodology employed. Since I used the lower bound earlier, and to make the math easy, I'll use the upper bound here - $10 million.
So, crunching these numbers together - $3 trillion/$10 million - I get 300.000. In essence, the US government should be indifferent between having 300.000 Americans killed or spending $3 trillion on the war on terror. This is the equivalent to the population of a smaller US city. However, this cost has been borne over 10 years, thus it would equate 30.000 deaths per year, the equivalent to an average small town being wiped off the planet per year.
Breaking it further down to a monthly basis (and with some very creative rounding) it's pretty much the equivalent of avoiding a 9/11 per month.
Too costly or not too costly? You may judge for yourself. :)