Words other than luck can be used in situations such as this e.g. fate, destiny, fortune, nature. But some of us are inclined to look for the person/s at blame due to their action or inaction. When we can't find someone to blame we sometimes resort to supernatural explanations i.e. God did it or it was good or bad luck. Personally. I think sh*t sometimes happens and it is pointless to suggest reasons that make no sense.