I believe in selfishness

I believe that every person has selfishness embedded in them from the day they were born. Selfishness is not taught to toddlers, they merely discover it within themselves. Selfishness can bloom from many different events in life, whether they are significant or not. Kids discover selfishness when they happen to play with other children and there are less toys than there are kids. Adults discover selfishness at the instant they taste success. They can't get enough of it.
Now what is the definition of success? Success, to me at least, is an act that only benefits yourself and quenches only YOUR desires. People who are addicted to things like smoking or drugs, don't understand that this act does not only affect them but their families and people around them. Those types of people are selfish. I've had my share of selfish moments but, as best as I can, i try to be selfless especially with the ones I care about.
My friend was telling me about someone who was making her life miserable. It was someone I knew, someone I was actually friends with as well. She would tell me all the teasing and taunts he would do to her and she got quite upset about it and one day i was fed up and angry FOR her. So i stood up for her to him. I told him to back off and stop bothering her and even though this act of mine could've cut of MY friendship from him and make him angry at me, i still went on ahead and did it. Because i expected that she would do the same for me. To be selfless. But i was wrong.
Coincidentally I had experienced the same thing she did some time later on in the year. A boy we both used to know and we both used to be close with had started bullying me online through Facebook. We weren't friends on facebook but he was friends with people that I was friends with and therefore saw posts that were relevant to me and would begin to comment rude things on them about me. It was humiliating and very public. EVERYONE saw these posts and yet, NO ONE did anything. I had to do it myself. I had lost faith in all my "supposed" friends. I knew the only reason they didn't do anything was that they were friends with him too, and defending me would mean losing him. They weren't willing to take the risk. I had lost my trust and began to believe in selfishness.