Not everyone believes in karma, or the fact that you reap what you sow. But I've seen many people go through what looked to be karma, due to the fact that they had hurt another person in the same manner they ended up getting hurt by someone else. And when this happens, the people who do others wrong usually don't feel like they should have to be put through the same thing.
But karma is necessary, because how else would people know how they really made someone else feel, and how else will they learn not to intentionally hurt other people. Of course, there are still some people who will never learn from their mistakes though, no matter how many times they face karma.
