A villain known as The Joker is threatening to destroy a number of important pieces of infrastructure in Gotham City. The police commissioner has estimated that with an expenditure of $10 million per week (the city does not pay taxes), they can reduce the risk of an attack by half. Assuming an initial probability of 30% that the attack will succeed and no one is actually injured in the attack, what is the minimum amount of economic damage the Joker would have to inflict in an attack to justify this expenditure?