As vohu said, most cities/countries lose money…. lots of money. They have to build these massive venues, which largely never get used again. China was smart in that they designed much of their olympic infrastructure to be quickly/easily converted into other things that they wanted to build already. Even so, they demolished most of the buildings almost as soon as the summer Olympics ended, and STILL lost money on the whole thing (that’s as a federal government though, economic impact on the economy would probably be a net positive of significant proportions).