Why did nick move to New York in The Great Gatsby?
At the opening of the novel, Nick has finished college and is prepared to set out an a career in finance. He intends to learn the bond business. Additionally, he hopes to become a sophisticated person and a scholar. He brings certain books with him that demonstrate this intention. More importantly, he brings certain social expectations with him.
Nick is surprised to discover that the people he had hoped would be suave and sophisticated are, instead, petty squabblers caught up in their own dramas. Instead of reading the classics, they read books suggesting white supremacy. Instead of discussing ideas, they go into histrionics about affairs and gossip.
The hopes that Nick had for finding sophistication in the east are ironically "fulfilled" only by Jay Gatsby, a fraud without much formal education beyond a single post-war course at Oxford.