The child didn't do his homework, so I beat him.
The beaten child felt resentful and went to beat up the cat.
The cat howled in pain and knocked over a flowerpot on the balcony.
The flowerpot hit me as I was leaving for work.
After my death, the child had no one to look after or protect him, and ended up having his kidneys and retinas harvested, dying a tragic death.
In this series of events, some attribute these actions as being the result of negative emotions accumulating and ultimately turning to harm the initiator.
In reality, it was purely bad luck.
Having so many factors come together and causing a problem concurrently is, to begin with, a rarity.
It's much like how, despite most of the universe being uninhabited, there always seem to be people who believe that the emergence of civilizations is the norm.
Every mistake that has a chance to happen will occur if repeated enough times.