I agree with the OP wholeheartedly. The world is a terrible place to live, and humanity is a terrible race of monkey-things. I thought that was already pretty obvious though. Saying "Life isn't fair" is like saying "grass is green".
If it's only coming to you now, though, then does that mean at some point you thought everything was a scene out of a Disney movie? People keep saying "Life isn't fair" as though it should be fair, or that it had been fair at some point. Who says that life should be fair? For that matter, who gets to decide what fair is?
Overall, it's moot point. Since you're already an atheist, you're not far from nihilism. Once you realize that there is no greater creator being, then you have to ask yourself the same questions humanity has always asked. "Why am I here?" "What is my purpose?"
Simple. You're here by accident. From the big bang, the universe expanded into a near infinite number of planets. Statistically, at least some had to be fit for life. If you can agree that your existence is accidental, then it also means that it is meaningless. Just a random cosmic incident, without any inherit value.
Once you understand this, you don't really have to worry about the state of the world anymore, or even about your own existence. You're going to die. I'm going to die. This entire world, the human species, even the universe itself will one day end. Nothing is eternal. Accept this, and it no longer matters whether or not life is fair, because pretty soon (speaking in a cosmic perspective) you'll be dead and nothing will matter to you anymore.
Even if you managed to do something world changing, how long will it be before you're forgotten? A million years? A billion? Trillion? Eventually, even the human race will die, and with it any memory of who you were and what you did. Your misanthropy is understandable, but it's also irrelevant. Everything is irrelevant.
It's an extremely cynical viewpoint, but also the one I find most logical. It might sound like a tragic philosophy, but I actually find it rather relieving. I have never complained about life not being fair, because I know that life doesn't really matter. Since this is my only life, I am motivated to do the very best I can, but even if I fail, I can console myself on the fact that it doesn't really matter.
So then, what was the message I was trying to convey? The point I was making? It is this: If you have a problem with society, devote yourself to solving that problem. Nothing was ever accomplished by complaining. If you don't want to do that, then simply take solace in the fact that society won't always be this way. The society you live in will one day end, and so will you. So why worry?