>>17769996 (OP)Latin America, particularly Argentina, benefited greatly from WW1, although I wouldn't go far to say they were its ultimate winner.
I'd say there are more examples of countries being neutral for most of the war that came in at the tail end seeing the greatest benefit. The Persians in the Peloponnesian War, Sweden in the 30 years war, and America in both world wars are some good examples.