How much does it cost to host the Summer Olympics?

How to get close to this number

Add the components. Several new venues at hundreds of millions each, an athletes' village, transport upgrades, security for two weeks and the operating cost of the event itself. Summing those gives a figure in the tens of billions for a modern Summer Games.

The overrun finding in the explanation is the genuinely useful one: every Games since 1960 has gone over budget, with an average overrun of a hundred and seventy-two percent. Not most — every single one. A category of project with a hundred percent failure rate on budget is not suffering from bad luck; it is structurally mispriced at the bidding stage.

The reason is that the bid is a competition. A city wins by promising the lowest plausible cost, which selects for the most optimistic estimate rather than the most accurate one — and the winner is contractually committed before the real number is known. Any process that awards a contract to the lowest forecast will systematically overrun.