>Asking why smart people aren't happier is a bit like asking why people who can jump high aren't more empathetic.

I laughed at this. However, I have to slightly disagree. I think there is a connection. I find the smarter people I know are actually happy, but they tend to be people who read books, who follow the news, and who care about the world at large and that is something that can easily make you sad. I'm not saying you need to be extra smart to do those things, I'm saying that smart people tend to do those things more than others.