Every action by animals (humans included) is done to sustain themselves. It may be stupid, inefficient, or done under delusion, but it's always a rational decision driven by instinct. It's a bit of backwards science, but if you keep that in mind, you can almost always judge people and their actions accurately. Put more simply, I have not yet seen evidence that selflessness exists or is even possible.
We seek power (money, favor, influence, etc.) because we seek to secure our ability to sustain ourselves. Perhaps we open doors for good favor, hope that we'll improve some collective attitude, or because we would want the same done for us.