I think you're wrong about this -- as I understood it, the term is a relic of the cold war. "First World" nations were aligned with the US, "Second World" were

I think you're wrong about this -- as I understood it, the term is a relic of the cold war. "First World" nations were aligned with the US, "Second World" were communist or communist-aligned, and "Third World" were not associated with either. After the collapse of the USSR "Third World" became primarily associated with impoverished nations.