Into the New Year

How is it that some people are made to be selfish? They don't seem to care about making anyone else feel good about themselves, do things for others or generally be helpful. This mindset I do not understand. I can't function that way and I wonder why? Day after day I expect to get the same treatment that I give to others and remain astounded when that doesn't happen. Why does this still surprise me? Is it my optimism that makes me feel that one day the light will shine down and other will change? Am I mentally unbalanced? Do I fit the definition of insanity? Maybe I should start talking to myself and get it over with.