In the video, what parts of personal finance does Benartzi argue that the average American is not doing well with? What
are some reasons, including behavioral challenges, people
don't manage their money well for the future?

Hi!

  I'm working on the same course and can verify the answer for you. The answer is that one out of 10 are saving enough. Nine out of 10 either cannot save through their 401(k) plan, decide not to save -- or don't decide -- or save too little. We think we have a problem of people saving too much. So we talked about all sorts of behavioral challenges having to do with savings eventually. Whether you think about immediate gratification, and the chocolates versus bananas, it's just painful to save now. It's a lot more fun to spend now.

I hope this helps you, I used this answer from the TED X talk and got a 100%!