After Yahoo: Why do powerful people lie?

Why do leaders risk so much over what, in the grand scheme of things, is a small dishonesty?

This article was originally published by Fortune.com on Wednesday, May 16, 2012.

By Katherine Reynolds Lewis, contributor

FORTUNE -- In the wake of Yahoo CEO Scott Thompson's departure amid controversy over his padded resume, the question remains: why did he do it?

Whether Thompson embellished his bio with a college major he didn't earn, or simply signed his name to a document that someone else falsified, the lie cost him a flourishing career. It also added him to an ignominious list of powerful leaders who stepped down in disgrace over resume deceptions, including former RadioShack (RSH) CEO Dave Edmondson and Notre Dame head football coach George O'Leary.

Why do they do it? Why do they risk so much over what, in the grand scheme of things, is a small dishonesty?