David Laibson, an economist at Harvard University, believes that the problem is lack of self-control.

ECONOMIST: The sorry state of saving

The problem is what is called self-control bias in behavioral finance.

FORBES: Savings: Start Early

The spam problem has been brought under control because a few smart firms, out of their own self-preservation, made it their business to get these problems under control.

FORBES: How Spam Was Solved

Lists "can help some people stay away, but for most people merely signing a self-exclusion list won't control that urge, " said Keith Whyte, executive director of the National Council on Problem Gambling.

WSJ: States Rethink Gambling Limits