Why might Fitzgerald want to underscore an important theme, such as the pursuit of wealth, so early in The Great Gatsby?
Nick Carraway made the decision to move to the East and learn "the bond business" because "everbody I knew was in the bond business, so I supposed it could support one more single man." One of the prime goals of young men returning from fighting in World War I was to become rich, so Nick was following the pattern of most of his peers in attempting to secure a position that would allow him to accumulate personal wealth.
Fitzgerald wanted to make the characters in The Great Gatsby very representative of the lifestyles and attitudes of that age group in that time. The drive for wealth went along with the search for the good life as demonstrated by conspicuous consumption of alcohol, lavish parties, and hesitation to become entangled in deep and lasting relationships. The American Dream, and the search for how to achieve it, involved the pursuit of wealth.