The UC Berkeley psychologist Dacher Keltner has found that, in many social situations, people with power act just like patients with severe brain damage. "The experience of power might be thought of as having someone open up your skull and take out that part of your brain so critical to empathy and socially-appropriate behavior," he writes. "You become very impulsive and insensitive, which is a bad combination."
Of course, we live in an age when our most powerful people - they tend to also have lots of money - are also the most isolated. They live in gated communities with private drivers. They eat at different restaurants and stay at different resorts. They wear different clothes and skip the security lines at airports, before sitting at the front of the plane. We shouldn't be surprised that they're also assholes.