Karma is most often understood by people who haven't studied or understood it. Karma is not the only thing that can be behind a negative or positive event.
Negativity seeks positivity so it can neutralise itself.
Positive natures draw to them negative responses ... because the world is ruled by negative selfish seperate selves. The greatest beings suffer the most. This often occurs because the Universal Spirit forges its best tools in fire.
The best way for a person to react, is to see the lesson in the experience, realise what life is communicating to you through the experience and the change. Such a change will insure that the mistake will never be repeated, and thus your future 'nows' will be different' [Extract taken from The Lost Teachings Of Atlantis by Jon Peniel].