People tend to give the minimum effort always. We look for our own interests and act in the way it's most convenient. We try to brake the rules (rather than debate them in a civilized way), impose ourselves before others, let others take the blame for our actions, "streetwise-ness", etc. You feel good when you get away with it.
You must always be one step ahead. You must always protect yourself, since they wouldn't care whatever happens to you. Unfairness, bullying, crime, etc., they are all manifestations of the same thing. It's funny how people criticize politicians, and yet they act the same sneaky way in their everyday life.
Egoism is often understood to be a consequence of our finitude. Since life is short, we want to have as many things as possible while we're alive. Therefore, it can't be helped. No one is saying egoism is bad or good, it simply is. Your actions (even the altruistic ones) somehow benefit yourself, otherwise you wouldn't be doing them.
The truth is, if people don't care about something, they'll never put any effort in it. What an individual considers important can only be decided by the individual himself. So, what should you do? On one hand, you should only care for yourself. On the other hand, you can't live alone; thus, you must understand what people close to you consider important and work based on that. Or, you can just continue not giving a shit, since that's what everyone always does.