Why do we not like people who are good at things?

Why do we sometime not like people who are really good at things, like sports, music, art, or school? Is this fair? Are adults like this?

We sometimes don't like people who are good at things simply because we are jealous. Most human beings are very unsatisfied with what they have or are. When people see someone who is better at something than them, they get mad and jealous. I don't think it is fair to not like someone because they are better than you. I do it too, but it is wrong. You should give everyone a chance even if you think you don't like them. I think adults are like this too because they get unsatisfied the same way as teenagers do.