It is hard for many people to cope with losses and mistakes made, they get stuck on it, which hinders their personal growth. Sometimes a person lives all his life with his problems that have not been solved when, or regrets to the end of his life about the mistakes made in his youth. This is all nonsense, you need to live here and now, and not in the past or the future.
I think this is primarily due to their education, upbringing and life experience. People who grew up in easy conditions are harder to endure difficulties and losses, because in their life experience there are few such situations.