We are the makers of our own universe
On the quantum level, particles act differently when observed and when not observed. It is believed the observed differences is due to what the observer believes is going to happen influencing the behavior of the particle. These experiments show how we subconsciously control our environment.
When an event occurs that we do not understand we try to explain it within the realm of our understanding. An example would be the spread of illness. Prior to the knowledge of bacteria it was believed that illness was caused by an angry God for your sins or because you were cursed by someone wicked. We now know this isn't the reason but at the time it made perfect sense to those claiming this was the case.
Therefore, I believe it is us who search for reasons to what happens in our lives. In an attempt to make sense of things we do not understand, bring closure, find peace, and nurture hope for the future. There is something reassuring in the thought of karma - someone bad getting what they deserve, eventually. Just as there is something comforting in finding a reason that something bad happened to someone who is a good person.
Finding the reasons that something has happened gives the illusion that it happened for a reason.