why do we like to tease others?

Long long time ago,I found a strange phenomenon .People always want to tease others. Treating the people much stronger than them they would like to conform them.However dealing with the people weaker than them they would like to despise them.
Is this the nature?Maybe .Since in my senior high school I found this.Most of my classmates respect the people who studied well.However referring to the students who were very diligent but still got poor marks they usually regard them as idiots. Maybe they believe they are much more smarter than them. Smart or foolish brain is given to you when you came to the world . Everyone has the reason why she (or he) come to the world. Learning is not his speciality .Study is only one part of our life it is important for it may affect our life .But it does not mean if you do not have a certificate you will never become a great man. Am I right? Currently I found the beauty is the widely used in our life.Do you like beauty ? Yes I am sure I like the beauty.In some way I really want to judge the appearance of others.But I really do not regard the girls who are not beautiful don’t have the chance of making up dressing up.Everyone want to be attractive .Sometimes I really do not know why people say they are vomiting while coming across a not beautiful girl wearing a colorful dress. Beauty or ugliness is also the same.Maybe you are popular because of your beauty. But this is not the reason of you teasing at others. One day your beauty will fade as the time goes on. Can you imagine the scenario that the young beauty laugh at your winkled face?
Now I still remember the words that my former English teacher told me” Everyone has own characters, you have not right to judge others.”Until now I still think over the meaning of the words. You are the only one in the world ,no one can replace your position.Do what you really want and mind your own business . Let the crowd chirps .(the Chinese slang)