There is a discussion about whether people can learn more from failure or success. I personally believe people can learn more from things they did wrong than when they did right. The following passages will try to describe why.
First, failure teaches people something they did not know. When people know what they did not know, they can train and improve those specific areas. Second, failure usually leaves a deep negative feeling. People do not like to have those experiences and will try their best to avoid it in the future.
Meanwhile, success obviously brings happiness and good memories. However, happiness and good memories usually lead to complacency. Sometimes it masks the real condition that probably still needs improvement.
Being too comfortable and complacent mostly make people hesitant to be better, while hardship and failure can become fuel for struggle and self development. Therefore, I believe failure teaches people more than success.