Boom, sorry, been busy as hell today and haven't had time to hit this adequately.
The military is struggling right now in a number of ways as is the largest single job producing and manufacturing industry left in the country known as the military industrial complex. This is due to the pissing match between house GOP and Obama and the idiotic Sequestration and Continuing Resolution crap. It's not so easy to categorize the defense budget into the B4 (Bodies, Beans, Bullets, Bandages) as most people are quick to do. Simplification and marginalization of this situation as the OP did is akin to making the asinine analogy towards the budget that if you are required to balance a checkbook, then you should be able t balance the budget. Not sure if OP was doing his usual trolling or if he is really that simple and lacking in understanding of what the DOD budget consists of and how the procurement budget process works.
To understand where the military stands right now, in most cases, outside of a couple of select industries within the Defense world, everyone had to make a choice on how to spend the reduced funds they received. Tradeoffs were made, for instance, parts or upgrades to obsolete hardware, not to mention the extreme focus on information assurance (IA) that began just before sequestration occurred and the DOD pushed into the digital age. In a lot of cases, funds were tied up from budgets prior towards commitments that in many cases the DOD was not meeting towards their vendors (Defense Companies) in contracts they already signed up for.
You would be shocked at the sustainment costs of existing programs, ie. ECPs (Engineering Change Projects) to address obsolescence issues with hardware and gear. As we have moved into the digital age, think about the operating systems pushing a lot of these computerized systems and the speed that technology advances. There are horror stories of bugs developing within the software and hardware systems making them unreliable and there being no dollars to resolve them.
You also have spares packages required for every program which falls also in the sustainment category. The older the equipment the more it costs to upkeep. This is why you see a never ending and perpetual cycle of Tech Refresh or new equipment development. In most cases, companies don't develop on IRAD (Internal Research and Development) like they use to. ie. build a widget and then market and sale said widget. Then, once there was a buyer, the cost of that IRAD would be eaten up in the purchasing of said widget amortized over the life cycle. In the economy of today, companies have had to trade IRAD for sustainment of personnel and facilities. What now happens is that companies are relying on concept procurement. Gov't levies a requirement through the release of a TRD, companies go and say, I can build this widget for X dollars. Then the Gov't will select a couple of vendors to build a prototype through a PRTA contract or even a prototype contract. After that, they'll push into a "Fly Off" through a series of Operational style tests. Again, funded by the Gov't. After the selection of the vendor, the procurement is broken up into LRIP contracts and ultimately into FRP contracts and then into the Sustainment ICS/CLS/PBL type contracts. All the while, the Gov't is footing the bill for every phase of this development. Very costly, right? Well, all of that slowed to a crawl in the last half decade.
I could probably write for another 5 or 6 paragraphs on this and how some of the left's sacred cows (Environmental elements) drive costs up. We all own, both sides owe the behemoth of the budget for a variety of factors.
Get the point?