Europeans always make fun of Americans for not having free healthcare or a comprehensive social safety net because all of that money goes toward building up our military. Well who benefits from that military? If the US wanted to be isolationist, it could be. We have two oceans and two allied nations on our borders - all we need for defense is a nuclear program for MAD. America’s conventional military operates almost entirely for the benefit of allied nations: protecting shipping traffic in the world’s oceans, offering protection to Eurozone countries, and giving military aid to strategic nations.

European countries haven’t needed to build up their own militaries since they know they can rely on the US to protect them, so they are able to divert those funds to comprehensive social programs. Why should they be able to have their cake and eat it too? They least they can do is help the US subsidize its own social programs in exchange for military protection.

(I know the real answer to this has something to do with the USD as a global reserve currency but I skipped that day in macro.)