Why do people think they can insult redheads?

People can be cruel I guess it's just easier for some people to insult red heads when there aren't many around which is the case being that ginger folks (sorry if that is offensive) are small minority being 1 out of every 2000 people in the U.S. People can spout things easily when someone is alone but when that person has a big group with them then they will be less likely to say something bad.