At the University of Amsterdam, researchers have found that semi-obnoxious behavior not only can make a person seem more powerful, but can make them more powerful, period. The same goes for overconfidence. Act like you’re the smartest person in the room, a series of striking studies demonstrates, and you’ll up your chances of running the show. People will even pay to be treated shabbily: snobbish, condescending salespeople at luxury retailers extract more money from shoppers than their more agreeable counterparts do. And “agreeableness,” other research shows, is a trait that tends to make you poorer. “We believe we want people who are modest, authentic, and all the things we rate positively” to be our leaders, says Jeffrey Pfeffer, a business professor at Stanford. “But we find it’s all the things we rate negatively”—like immodesty—“that are the best predictors of higher salaries or getting chosen for a leadership position.”

Pfeffer is concerned for his M.B.A. students: “Most of my students have a problem because they’re way too nice.”

He tells a story about a former student who visited his office. The young man had been kicked out of his start-up by—Pfeffer speaks the words incredulously—the Stanford alumni mentor he himself had invited into his company. Had there been warning signs?, Pfeffer asked. Yes, said the student. He hadn’t heeded them, because he’d figured the mentor was too big of a deal in Silicon Valley to bother meddling in his little affairs.

“What happens if you put a python and a chicken in a cage together?,” Pfeffer asked him. The former student looked lost. “Does the python ask what kind of chicken it is? No. The python eats the chicken. And that’s what she”—the alumni mentor—“does. She eats people like you for breakfast.”