I think there's an important psychological dimension that's often missed from these calculations, particularly for countries that have a chip on their shoulder. It's a way for the entire world to be focused on something that you're doing well (hopefully) for a few weeks. Before the Beijing olympics many Chinese would ask you how you liked China, and when you replied, "yes" they would say China is "luo hou", which means backward. China is still luo hou to most who don't live in the richest eastern seaboard cities, and being able to watch China do something amazing for weeks on end is more than worth the 40 billion that was spent.

Lets not forget that in developing countries, massive investments are often sped up just to get the opportunity to bid - in 1999, the Beijing subway was almost nonexistent. Today it's one of the largest systems in the world, and was largely constructed prior to the Olympics. Other improvements included the Beijing airport. Of course, you could say that I'm cherry picking the Chinese olympics as one of the few examples, and maybe there aren't many advantages for a city like Tokyo or London, but even here in the UK, many people were inspired and proud of how their country handled the events. That may not be worth what it cost, but it is worth something, and I think it's a bit bizarre that the Economist seems to be puzzled as to why these events poll well with voters.