I don't know why you. Hate yourself. I don't know you. But, life is painful if you detest yourself. Cognitive behavioral therapy could help to deal with this effectively. Sometimes we have really distorted thoughts about ourselves. When you learn to look at the world and yourself realistically then you can start to come to peace with yourself. Take care.
Self-loathing. There are many underlying causes of self-hate. Some have experienced trauma or abuse, others have a very negative self-image. Some individuals have an ongoing dialogue of negative thoughts. Generally it takes a fair amount of time and psychotherapy to help a person work through this situation/condition. A thorough evaluation can help identify the specific factors that underlie your situation.