The self is a horrible thing. We either hate it because it is not good enough and feel depression or we love it and act arrogantly. The self exists by virtue of mental comparisons to other people and imagined standards of where we should or ought to be. In the bible, when Jesus refers to being meek he is not saying we should be pushed around by others, he is saying we should be self-less, that we should not be pushed around by our "self". Buddhists are very clear - the self is a delusion that causes suffering
The self is a way of framing reality. This way of framing reality is built into us through evolution. It has helped us to survive and passion our genes. It punishes us for not doing as well as others and rewards us for achievements, but only briefly, then we must work on the next achievement for the next reward. The evolutionary origins and the way this system works to drive us with punishment and reward are quite well understood. The big question is whether there is more to us or not, whether there is an alternative way of being that allows us to escape this endless oppressive cycle of reward and punishment.
The good news is there is an alternative way of being. Many people have experienced at least transient glimpses of if it and others who have trained themselves selflessness can experience it quite a bit. The first noble truth in Buddhism is the existence of suffering. The second is the cessation of suffering. Suffering ceases when we achieve a goal but Buddhists do not count this because that momentary release sets up the next cycle of suffering. It is like a drug addict who takes a hit, it relieves suffering briefly but the need for the drug is increased and so suffering is increased. Instead, true cessation is more like getting clean.
In science there is a debate about whether or not it is possible to step out of the system of selfishness. Some evolutionary psychologists would prefer to keep it simple and explain all human behavior with this one system. For them, claims about stepping out of this system are delusional tricks we play on ourselves. We claim we are free but really we have just found a clever new way of comparing ourselves to others, we have opted out of one reward system where we were loosing and stepped into another where we get to win more - before I was not rich so I was a looser, but now I am spiritual so I can look down on the rich and win. Unfortunately, they are not entirely wrong as religion often does function this way.
The good news is that it is possible, that there is an alternative way for our brains to function. The evidence has been with us for a long time in the form of genuine spiritual achievement. Also, in my opinion, the existence of mirror neurons is related to this. I have a Ted talk somewhere in this blog on evolution, brains, and the question of selfishness that addresses this from a scientific perspective. However, on the practical side, ranting about the horrors of the self, which is what this is, is important for building up a defense against falling back into the cycle. Quitting the self is very much like an addict quitting a drug - because it is neurologically the same thing. Both involve being trapped in a cycle of desperately trying to trigger our neural reward centers.