Most people that feel that they have been wronged also feel that they would like a revenge of some sort. Wanting revenge is a human condition that mankind cannot seem to grow out of.
Buddha's message is that people that cause purposeful harm to others will usually have some event happen in their life. The key is that the harm is purposeful.
I overheard a man chastising a woman for a perceived wrong that he thought she had done to someone else, and it was obvious that he did not know the whole story. He told her that karma would get her. First, he interfered in something that was not his concern; he just like to point out people's faults. Second, when you interfere without permission, but think you are acting for someone's best interest, you are creating a harmful act. Third, she had not done any intentional wrongs; she was acting in her child's best interest as the child's only caretaker. Fourth, there was huge irony in the fact that the man cited karma as her punishment when he was the one actually doing something harmful.