If anything, surely it's the Americans who are leeches, what with the fact that they're living off software exports and monopolies as opposed to production of actual useful goods?

Do you think we didn't invest in our defence? Here in Sweden we put in 5% of GDP until the Soviet Union dissolved. It was pro-US politicians like Carl Bildt, a man who associated with US intelligence, who reduced defence spending. We had nuclear weapons and refrained from assembling them on a US request in return for being under your nuclear umbrella.

Hegemony isn't charity. It's expensive. What the US gains is an invitation to exert power all over the world from bases and ports within countries playing a willing role in the US position. It gains the US dollar as the reserve currency and petro-currency of the world. In particular, without the world accepting the US dollar as the reserve currency, the US's ability to maintain a large budget deficit evaporates.

To gain this sort of power without invitation and strong alliances built on shared understanding and trust will cost the US much, much more in the longer term.