It's a jobs program. Someone has to employ all those boys who majored in the humanities at the academies and other feeder schools for the officer corps.
The MIC is about spending as much money as possible.
Officially, it's $721,531,000,000 FY2020
"In 2018, it was announced that the Department of Defense was indeed the subject of a comprehensive budgetary audit. This review was conducted by private, third-party accounting consultants. The audit ended and was deemed incomplete due to deficient accounting practices in the department."
https://en.wikipedia.org/wiki/Military_budget_of_the_United_...