The point of private contracting should be to deliver more for less, not substitute an overbloated government bureaucracy with an overcharging private monopoly.
Well that is what has happened. It began under Clinton, with Al Gore's reinventing government, bringing the efficiency of crony capitalism to government operations. Bush / Cheney continued it. The Halliburton scandal is real. It's just that at that point everyone was doing it. Why have a soldier do something when a private contractor could do it at 10 times the cost.
Total federal employment has not increased in years. Salaries have been pretty well capped for a decade or more. Where your money is going is to the private cronies.