In "Winter Dreams," what indicates that Dexter is an ambitious young man?
Dexter from this Fitzgerald short story is much like the author's most famous character, Jay Gatsby. They are both from Minnesotan families and long for a better, glamorous life away from their upbringing. Dexter begins working at a young age, showing his ambition. And, he knows that caddying for rich golfers is no way for him to escape his tedious life; so he refuses to caddy for a little girl.
Another example of his ambition is his willingness to pass up a sure thing (a business course that his dad could have paid for) in order to pursue a more prestigious education out East. Just like James Gatz, Dexter makes a plan for his future early on and successfully carries out the business part of it (if not the personal part).