This form of the utility function describes the real behavior of people quite well. Agree that the fifth consecutive chocolate donut with chocolate filling and chocolate chips brings less pleasure than the first. Similarly, the fifth billion brings less joy than the first. Let's take the next step. Let's assume that there is not one rational investor in our economy, but many. Each of them will prefer the action that will protect them from losing their jobs. What if the risk of losing a job by one investor is correlated with the loss of a job by the others? This is a reasonable assumption.