If we have this much surplus, clearly we're buying too much. I know that if I find myself giving away cans of green beans, I make sure I don't buy a whole pallet the next time I'm at Costco.
Not necessarily. Following 9/11, the U.S. began two major wars in Afghanistan and Iraq under the Bush administration. Under the Obama administration, the U.S. has withdrawn from Iraq, wound down operations in Afghanistan, and begun to reduce the size of the army. As a result there is going to be a lot of equipment that simply isn't needed anymore; if we're not longer engaged in counterinsurgency operations in Iraq for example, we don't need all those MRAP vehicles anymore. So what do you do with all this crap? One solution is to give it to the local police, but as we seen if you arm them with the tools of an occupying military force, they start acting like one. Another would be to give it to the Iraqis and Afghans or whatever regime we're trying to prop up this week... but as we've seen in Iraq, these weapons have a way of changing hands and now we've got ISIS militants armed with M-16s and driving humvees.
It seems logical to try to find a use for all this material but arguably giving people weaponry tends to fuel conflict. We saw something similar happen after the end of the Cold War. The USSR and Warsaw Pact countries produced millions of AK-47s with the idea that they could hand them out to peasants in case they ever got in a fight with NATO. After the fall of the Berlin Wall and the collapse of the USSR, you had all these extra guns nobody needed. Enterprising people figured you could make a lot of money flying them into conflict zones in places like Africa, fueling civil wars and militias.
Eisenhower said that war was humanity hanging on a cross of iron- that "every gun that is made, every warship launched, every rocket fired signifies, in the final sense, a theft from those who hunger and are not fed, those who are cold and are not clothed." But its worse than that- those billions of dollars spent after 9/11 in the name of defending our freedoms are not just stolen from the American people, but are now being used to oppress them and spy on them.