One day at lunch I was talking about how people, especially at big discount stores, will circle the parking lot searching for the closest spot regardless of the fact that they see others doing the same thing unsuccessfully. A coworker identified this as a form of 'herd mentality' and I agree that it is. A thinking person realizes that its futile to go searching for the closest spot as it almost always prolongs your trip. We as people, go search for the closest spot because everyone else is doing it
... Most people vote in much the same way. They blindly follow politicians like they would choose to pull for a pro sports team, except that they usually know a good bit more about the sports team's record.
I watched a line of cars circle a bowling alley parking lot one Saturday, all thinking they'd be the ones to get the closest spot. They pulled in one after another and followed each other to the front entrance, realizing there were no spots, and then heading toward the back of the lot where the closest spot would be. It was like a line of ants, one following the other and few realizing the act was a dumb, unproductive decision.
Look for examples of herd mentality in your everyday life and it will scare you to see how few people actually think for themselves...