Contracts are definitely awarded to companies based on their political connections, and not necessarily merits. Look at the whole Halliburton/Cheney shitshow in Iraq for a recent example.
We're talking $40 billion worth of (cost-plus!!!) contracts awarded to a company that was widely viewed as incompetent by the soldiers on the ground, followed by the vice-president getting a position on the board of said company when he retired. This is after he got a $30 million golden parachute after leaving them in 2001.
I think all big empires eventually collapse under the weight of excessive greed, systemic corruption and cronyism, where everyone from the top to the bottom is busy stuffing their own bags while everything crumbles around them ("f*ck you, I've got mine, go get yours")
It's just that the US manages to prolong this much longer than others.
More to your point, the book “Imperial Life in the Emerald City: Inside Iraq's Green Zone” by Rajiv Chandrasekaran is a scathing indictment on this system, and how incompetent apparatchiks were chosen over less politically connected entities, and how this had a direct hand in the result of the occupation. Strongly recommended!
Not stealing directly but US military industrial complex is a huge money sink which delivers much much less than civilian counterparts for the same money. F-35 story is a shame IMHO.
Corruption is a big issues in the west but compared to what's happening in Russia and ex-USSR countries, it's not even in the same ballpark, hell, it's not even in the same planet.
In the west we have free press looking into it and exposing the theft, plus, the theft in the west has very complex schemes to make it look legit on the surface and to make sure nothing sticks to our Teflon politicians, but in Russia they don't need to worry about any red tape BS, they can just shove their hands in the public purse and take as much as they want and go directly to the Lamborghini dealership or the casino without any accountability, and if any reporter looks too deeply into their theft, they get death threats or even death through very suspicious circumstances.
The problems on the Joint Strike Fighter program were caused more by flawed analysis of costs and military requirements than by outright corruption. Very little funding was stolen, and not many individuals have gotten personally wealthy from the program. Lockheed-Martin is now delivering an F-35 Block 4 product that, despite a few remaining minor flaws, substantially meets the customers' requirements. It's just that what the customers thought they wanted back in 1996 no longer aligns with what they actually need today.