[mac01021]

What is the nature of that horrible detriment to society?

There are myriad ways that humans tend to make bad decisions in the course of modern life. Psychology and evolutionary biology currently provide the best answer to "why".

If you want to understand yourself well enough to be able to avoid having marketers and advertisers make your most important life choices for you, or want to raise your children to think critically about statements they hear even when it means overcoming confirmation bias, or want to think about how to help society escape detrimental Nash equilibria that lead catastrophic global warming, a deep and accurate understanding of human behavior seems to me to be clearly better than simply operating under the wildly simplistic assumption that people always behave rationally in the pursuit of well defined goals.

[bigred100]

Well, my personal opinion is that a better understanding of human nature will come from the traditional means (interacting with people, study of literature and history and human institutions, and, even more controversially, maybe even religion) than trying to analyze human behavior from the point of view of apes dominating each other. I don’t think anyone with any reasonably sound theory of human nature would hold the assumption of “people [behaving] rationally in pursuit of well defined goals”.