Because someone has to do it.
No, they don't.
While a number of military operations have indeed proven their worth (such as, incontestably, the raid and killing of OBL), others, like the war and occupation of Iraq, have not.
The original goals of establishing a foothold in the middle east (possibly one less "opinionated" than Israel), getting a solid hand in the oil production in that area, reducing the threat of terrorism and others have just not happened. We end up spending billions of dollars and thousands of lives to get nothing. Nada. Zilch.
So now, with examples such as this STILL dominating the overall military expenditures documented, we call for the countries unemployed to go into training so we can spend money to send them somewhere else in the world?
How many soldiers do we really NEED? I am not saying we should disband the forces, but what the hell are we using them for now? The only thing I see that could be a problem would be defaulting on our bills to China!
Bottom line is simple. NOBODY on the opposition side has actually voiced any practical solution to this other than denial. They insult the messenger, they decry the movement, they create feces out of air and say that they are wallowing on it.
All of which do no more than slight the message in hopes it will be ignored.
If something like this has cropped up, to this scale and this duration, it is not just a "bunch of hippies and malcontents". The ones screaming that the loudest are the ones that are afraid of change and that they might somehow be considered less than they believe themselves to be because of it.