Because success generally changes things, while mistakes generally don't. You can't clone a previous success exactly, because its presence alters the environmen

Because success generally changes things, while mistakes generally don't. You can't clone a previous success exactly, because its presence alters the environment from the one in which it was initially achieved, and you have to account for that. You essentially have to show the same sort of creativity as the original success showed, and thus you haven't really learned much. By contrast, things that were mistakes in the past tend to still be mistakes in the present. Usually they continue to be mistakes in the future as well. That's something you can really learn from, as you go through the creative process toward success that you were going to have to go through anyway.