I think I understand your points here, since they are the same ones I first heard as a boy, some 50 years ago.
And in every election, politicians promise to fight against Pentagon "waste, fraud and abuse", and every new administration then claims to have "saved" taxpayers billions through their new "streamlined" procedures.
Indeed, it sometimes seems that what one administration hails as a great advancement in procedures, the next discards as just so much bureaucratic hummana-hummana.
That's ten new administrations now, and yet as near as I can tell, the problem is today described in exactly the same words as 50 years ago.
And that's why I'm highly dubious of any claims that some knight in shining armor is going to ride into town, to kill off all money-wasting "dragons" and "sacred cows". ;-)
Since, by all accounts, that's never happened before, why should anyone think it might happen now?
Bottom line: National defense, unlike so much else our Federal Government does, is a serious constitutional requirement, and yes, rooting out wasteful spending should be a daily responsibility of every manager at every level.
However, all that said and done, the nation must provide itself whatever defense it truly needs, almost regardless of the cost.
As for all those other Federal programs you mentioned -- Social Security, Medicare, etc. -- they are not constitutional, and should be overhauled both to protect beneficiaries and get that money out of Federal coffers, away from temptations to Congress to spend on other pet projects.
And exactly when will that happen?
Doubtless when those sacred cows come home... ;-)