Who is Herbert Foster from Welcome to the Monkey House and what is their importance?

Herbert Foster requests the narrator's service at the beginning of the story. At first it is unclear why Foster needs an investment counselor: he is a bookkeeper at a grocery store, a bartender on the weekends and barely earns enough money to keep his family fed and clothed. His life is very humble. When the reader finds out that Foster actually has fifty thousand in savings, as well as the eight hundred and fifty thousand in securities from his grandfather, it becomes unclear why Foster is essentially pretending to be poor.