The US is a global hegemon. Many people in the US think this is good, and funding for the military and DOD has a lot of support in congress. The welfare state is a boogyman on the right, to some extent. Sure, the US could pay for it, but it may not pass congress.

War is good business. The defense contractors lobby and donate to politicians who promote policy that allows the contractors to sell their products to whomever they wish, the more, the better. Conflict arenas are also necessary for the proof testing of new weapons. It's fairly simple. Medicare for all will end up costing corporations and the wealthy. They don't like that.

Rich people make money off of war.

Simple. The elites control the govt and profit from wars. They could not care less about the health of the masses and like the current for profit healthcare system.

There are a lot of questions that need to be addressed. I would like to know the establishments answer to Ocasio'ss though.

Untreated disease and injury are far more threatening to the typical person than overseas militants. Much of the money we spend on the military ought to be used for a universal healthcare system.

And no one will actually give a coherent answer.

Yeah...what she said! ?