US-based olympics are the only ones that have made money -- and the only ones that have massive stadium infrastructure in place beforehand. Not sure about the impact on the individual cities, though. I'd have a feeling that would vary depending on the city's financial situation, and Chicago's is bordering on disaster. Plus, like you said, having the necessary infrastructure in place would be critical, and having dumps like Wrigley and stupidly open stadiums like Soldier Field kill Chicago even just being able to host more American sports events, much less something like the Olympics.