It may sound cynical, but anyone who goes through life expecting 100% fairness is doomed to disappointment. From time to time, somewhere, somehow, you're going to be screwed over. Sometimes there are ways to redress it, sometimes there aren't, and you just have to swallow your disappointment, consider it a lesson learned and push on. That is why you have to learn to depend on yourself. The more you set yourself up to be dependent on others, the more "unfairness" you'll encounter.
Keep your personal integrity and by extension your own self-esteem intact, always take the high road, and you'll weather the slings and arrows of other people's iniquities.