Economists typically remind people to weigh the costs of an action against the benefits of that action. Let's invent some examples where it's just too expensive or too risky to solve the very real problems discussed in this chapter.
a. It's possible that it would just cost too much to defend the earth from asteroids, where the best option, all things considered, is just to hope for the best. Invent an extreme example where this is the case your example might take place in a world with different technology, different type of government, and so forth.
b. What about saving the tuna? Invent an example where the best option is to just let the fishermen do what they want, even if tuna go extinct.