This is a wellknown story:
One evening an old Cherokee told his grandson about a battle that goes on inside people.
He said, "My son, the battle is between two wolves inside us all"
"It is a terrible fight and it is between two wolves. One is evil - he is anger, envy, sorrow, regret, greed, arrogance, self-pity, guilt, resentment, inferiority, lies, false pride, superiority, and ego." He continued, "The other is good - he is joy, peace, love, hope, serenity, humility, kindness, benevolence, empathy, generosity, truth, compassion, and faith. The same fight is going on inside you - and inside every other person, too."
The grandson thought about it for a minute and then asked his grandfather, "Which wolf will win?"
The old Cherokee simply replied, "The one you feed".
http://www.psychologymatters.asia/article/65/the-story-of-the-two-wolves-managing-your-thoughts-feelings-and-actions.html
But why do we so easily succumb to feed the evil wolf? Why do we hate and feed it and react hatefull towards others?
Some people have the feelings to hate others because of insecurity.they insecure for what' others had or it may be about the beauty of one person.