Germany got rich in the postwar period from US funded reconstruction, as did Japan, Italy and a number of other countries the US occupied and wanted to prevent from re-collapsing. They "lost" but were propped up by the victors.
America's involvement in WW2 is very commonly understood to have played a decisive role in its economic and political power in the postwar. All the other allied countries had to create giant assembly lines during the war, but at the cost of having half their cities destroyed by air raids, and eventually losing the colonies they relied on for resources and markets. America never saw any attacks on its mainland at all, so it became the predominant world economy and moneylender alongside the USSR, with virtually every country on earth relying on assistance from either empire for the next 30 or so years.
America's involvement in WW2 is very commonly understood to have played a decisive role in its economic and political power in the postwar. All the other allied countries had to create giant assembly lines during the war, but at the cost of having half their cities destroyed by air raids, and eventually losing the colonies they relied on for resources and markets. America never saw any attacks on its mainland at all, so it became the predominant world economy and moneylender alongside the USSR, with virtually every country on earth relying on assistance from either empire for the next 30 or so years.