I'm not a military economist type, but I'll take a stab at this.
Apart from the costs you cite, which are certainly significant, there's the cost of replacing equipment, much of which dies quite quickly in the desert.
There's also the cost of oil (which the US buys, and doesn't just steal out of Iraq's oil wells, as far as I know). Believe it or not, the US military is the largest single consumer of oil in the world. Here's an interesting article about it:
From the figures in that article, I'd estimate that the US military uses about $10 billion a year in oil, at today's prices.
Contractors are a huge expense. From what I've read, there are as many contractors in Iraq as there are US military personnel, each getting paid much, much more than a soldier.
According to the following article, the US spent about $100 billion on contractors between 2003 and 2008:
Unfortunately, as outrageous as the money wasted on the war is, the human cost has been much worse, and it may not be fully paid for generations to come.
These are some very serious numbers you mention here. Just take a look at this TED talk - just $8 billion to halve the number of people without access to drinking water.
Imagine what can be achieved with hundreds of billions, if used constructively.
$100 billion on contractors? wow
Why can't the US military increase the pay for the soldiers, hire more soldiers and reduce the number of contractors? These contractors are in it just for the money, don't have any respect for laws/human life as blackwater has repeatedly demonstrated.
They should really think twice, thrice before starting any war, and especially an unnecessary one.
"Why can't the US military increase the pay for the soldiers, hire more soldiers and reduce the number of contractors?"
Soldiers aren't paid very much directly, but the indirect costs are huge, including at least room and board, training, and future benefits including medical care (via the VA system, currently almost $113 billion/year).
Quickly Googling for estimates of the cost gives answers between $350,000 and $400,000 per soldier per year.
So, to answer your question, we don't because it'd cost more.
Apart from the costs you cite, which are certainly significant, there's the cost of replacing equipment, much of which dies quite quickly in the desert.
There's also the cost of oil (which the US buys, and doesn't just steal out of Iraq's oil wells, as far as I know). Believe it or not, the US military is the largest single consumer of oil in the world. Here's an interesting article about it:
http://www.energybulletin.net/node/13199
From the figures in that article, I'd estimate that the US military uses about $10 billion a year in oil, at today's prices.
Contractors are a huge expense. From what I've read, there are as many contractors in Iraq as there are US military personnel, each getting paid much, much more than a soldier.
According to the following article, the US spent about $100 billion on contractors between 2003 and 2008:
http://news.bbc.co.uk/2/hi/americas/7557995.stm
Then there's all the money that's simply "lost". For example:
"How the US sent $12bn in cash to Iraq. And watched it vanish"
http://www.guardian.co.uk/world/2007/feb/08/usa.iraq1
There are no doubt many other expenses, such as the new $600 million "embassy" in Iraq (which is going to cost $1.2 billion a year to operate).
For more details see the Congressional Budget Office's report on the "Estimated Costs of U.S. Operations in Iraq and Afghanistan"
http://www.cbo.gov/ftpdocs/86xx/doc8690/10-24-CostOfWar_Test...
and "The Three Trillion Dollar War":
http://www.amazon.com/Three-Trillion-Dollar-War-Conflict/dp/...
Unfortunately, as outrageous as the money wasted on the war is, the human cost has been much worse, and it may not be fully paid for generations to come.