I attributed it to the currency being backed by aircraft carriers and figured we would be in trouble if we demilitarized.

I guess that’s a part of it. The other aspect is that it is underwritten by the strength of US economy, which, despite occasional hickups, is still the strongest economy bar none. Luxembourg or Lichtenstein may have a higher per capita GDP (dunno how they get their figures), but if US gets cold, the rest of the world is teetering on pneumonia.