Vanity Fair does not have much to say about intellectual achievement. Instead its main demonstration of intelligence lies in its characters' ability to plan, scheme, and maneuver strategically around others as they jockey for the best social and financial position possible. In keeping with the cultural stereotypes of his time, Thackeray gives women the edge over men here. Although we frequently see male characters engaged in recreational games of chance, it's the female characters who wager for the high stakes, deploying an innate, almost animalistic cleverness.
There is a way in which Becky and the narrator compete with each other. The narrator jokes, makes puns, and says clever and cutting things about the characters and actions he describes. The only character who is able to do all those things is Becky, and this makes the novel a kind of battle of wits.
Some strategizers and schemers in the novel are compared to gamblers (Mrs. Bute, for instance), while others are like military commanders (for example, Glorvina O'Dowd). But both types tend to fail and succeed at random. The novel is thus suggesting that even the best-planned military campaigns are like throwing a die and hoping for a good result.