"In 1950, America had a unique dominance of the "free world" and it could afford to be generous, so it was: We had more money than we knew what to do with, so we absolved our allies of paying for their own security. Thanks to American defense welfare, NATO is a military alliance made up of allies that no longer have militaries. In the Cold War, that had a kind of logic: Europe was the designated battlefield, so, whether or not they had any tanks, they had, very literally, skin in the game. But the Cold War ended and NATO lingered on, evolving into a global Super Friends made up of folks who aren't Super and don't like each other terribly much."