Why does Gatsby not get the $25,000 left to him in Cody's will? What lesson did young Gatsby likely learn from this incident?

From the text:

And it was from Cody that he inherited money — a legacy of twenty-five thousand dollars. He didn’t get it. He never understood the legal device that was used against him, but what remained of the millions went intact to Ella Kaye.

Gatsby likely learned that things don't always go the way we expect them to..... be prepared for let downs.