I think that Nick is trying to show us how he feels through his final line in The Great Gatsby. When he says, “So we beat on, boats against the current, borne back ceaselessly into the past,” it’s clear that he thinks of Gatsby’s life as tragic. He seems to be saying that while they were able to achieve some things together, they were ultimately powerless to change their fates: they were doomed to be stuck in the past forever.
I don’t think this means that Nick is disappointed in Gatsby for not living up to his potential; rather, I think it means that Nick thinks Gatsby was never really able to do anything with his life because of who he was and where he came from. If you look at what happened after Gatsby died, you can see that even though he did manage to make some money and get some status for himself, it wasn’t enough for him—he wanted more than anything else for people to remember him as a great person from a long time ago. And so when no one remembered him at all after his death, it must have felt like an enormous failure on his part.
