As an experiment, We prepare different chits and write down different stocks name on those piece of paper. Then we give it to different monkeys to pick it for a week. Few come out as a winner and few as losers. We continue playing the same with winners only. Over some time, one monkey comes as a right in all the time. The media calls that monkey a successful monkey and call everyone to understand his success mantra.
This is an outcome bias; we tend to evaluate decisions based on the result rather than on the decision process. When a person has a good performance track record of stocks picking then we consider him as a good stock picker or an expert rather than knowing the process or it can be possible that past results can be due to pure luck. I met few fund managers who do not read books or annual reports thoroughly but they have survived for 10-12 years so people call them successful and an expert.
In conclusion: never judge a decision purely by its result, especially when randomness or ‘external factors’ play a role. A bad result does not automatically indicate a bad decision and vice versa. So rather than tearing your hair out about a wrong decision, or applauding yourself for one that may have only coincidentally led to success, remember why you chose? what you did?. When we start understanding the process behind success, then we can easily recognize success as a part of luck or efforts.