Give and Take: From the author of million-copy bestseller THINK AGAIN

by Adam M. Grant

“The true measure of a man is how he treats someone who can do him absolutely no good.”

“You should be willing to do something that will take you five minutes or less for anybody.”

Sunk costs do have a small effect—decision makers are biased in favor of their previous investments—but three other factors are more powerful. One is anticipated regret: will I be sorry that I didn’t give this another chance? The second is project completion: if I keep investing, I can finish the project. But the single most powerful factor is ego threat: if I don’t keep investing, I’ll look and feel like a fool. In response to ego threat, people invest more, hoping to turn the project into a success so they can prove to others—and themselves—that they were right all along.