Selfishness is our natural instinct to take care of ourselves, even animals are selfish at certain times. We take care of ourselves then only we can take care of others. Due to the known fact that we live in a society, we are bound to control it but somewhere behind our mind where we are not aware of our selfish behavior.
Everyone is selfish. We all try to look after our families, our own children and just imagine as an example that if our children are not our children but some one else's children then we would not care for them like we do right now. Why we care for our family so much? Because we consider our family as our family if our family hurts us then sometimes, people leave their family because the feeling of that this family is our's gets away.
Selfishness is a requirement of nature to survive in this world. It's in the law of survival and nature to take care of ourselves to survive. There is nothing wrong in being selfish but not caring for others is wrong. We can be selfish enough to able survive financially, mentally and at the same time, try to help others.