For some perspective: Finalnd's military budget: 300 million US military budget: 700 BILLION The US could dump a lot of money into these social services to address people who are homeless, drug addicts, and other people on the fringes of society. We are however, constantly put in a place where other nations depend on us for their security. As such, they don't have to have a massive defensive budget when they can rely…
Resulting in a new wave of rearmament and arms races across the entire planet as everybody scrambles to build up their military in the resulting power vacuum. If you want to see another wave of all-out wars in your lifetime, well, that's how you get it.
The United States has been amply repaid for its military budget (despite it being put to stupid use by certain Presidents) in terms of global political and economic stability, which is good for business.