“In some ways this may seem obvious, but very few managers are able to be themselves in business. For example, an excellent co-worker (we’ll call him Stan) gets his first promotion to manager, and everyone is excited. But once Stan becomes a manager, he stops being Stan and becomes “Manager Stan”—and magically transforms into a dick. He feels like he has to establish his authority, so he stops treating you like a person and starts treating you like someone he has to impress with his power. Nobody likes or follows “Manager Stan.””

Stupid title, but quite insightful. I think we have all seen people change like this and, even worse, perhaps have done it ourselves?