huh. Argues that we should address problems where we can do a lot of good with relatively little investment. As an economist, he seems to be proud to take a rat

huh. Argues that we should address problems where we can do a lot of good with relatively little investment. As an economist, he seems to be proud to take a rational approach, but on the other hand, he is taking a view based merely on financial rewards ("bad projects — basically, projects where if you invest a dollar, you get less than a dollar back"). So let's assume money invested in HIV/AIDS prevention and treatment can bring more savings than fixing climate change (which is very expensive). How does it follow from this that a focus on HIV/AIDS would be more important? After all, climate change is an existential problem that may endanger the survival of our civilization.