You are by nature selfish. You have your underlying motive for everything you do. You do something to give you a feeling of happy satisfaction and enjoyment, or to fulfill your wish or desire, or to gain an advantage or profit from something. Through your self-centered nature you do something to obtain something – something that is beneficial to you, and not to someone else. This is nothing wrong in itself; it's just an indication of your uniqueness as a being.
Indeed, everyone is a special being and naturally each of you has your separate desires for different things. For instance, some long for a large house while others want a new or bigger car; while some crave for happiness, others strongly wish for vast wealth, believing that an abundance of valuable possessions or money bring happiness. You also have your own personal preferences in foods, clothes, recreational pursuits, etc.
Now the very fact that every one of you has your individual wants marks each of you down as a selfish or self-centered person. Nothing’s wrong with that. As a responsible and unique person, you can only make decisions in accordance to your wishes. In this case, you go after what you like. No one can deny that. You are responsible for your own life, to get what you want. Self-centeredness is not necessarily bad if practiced in a positive or constructive way.
Very often, you do not notice what a self-centered person you are when you pay particular attention to only yourself or what you want to do? You notice it only in others. Do you make your work or running your business the top priority over everything else? How often do you get into conversation with friends and those close to you? How much do you listen to them or do you do most of the talking? How much loving attention you pay to your loved ones whenever you are preoccupied with whatever you are doing?
Self-centeredness becomes negative only when people adopt an arrogant or self-important attitude towards others. They regard themselves as more important, competent, or cleverer than other people. They care solely for their own feelings and concerns. It’s not in their nature to acknowledge the views or think about the feelings of others. They can be very demanding and want things to go their own way most of the time, if not all of the time.
People who are self-centered can be excessively disrespectful. With such a negative attitude, they tend to be extremely unpopular with others who have somehow associated with them even briefly. This results in their inability to form lasting relationship. All their personal qualities of intelligence, ability, talent, etc become nothing if they remain incorrigibly self-centered. Their character and reputation are badly tarnished by their self-centeredness.