Symbolism, Imagery, Allegory
Toward the end of the novel, Amory Blaine becomes more and more of a socialist. His most radical belief is that people would still be willing to work hard… even if there were no such thing as money.
In his mind, human competitiveness doesn't really care about prizes; it just cares about triumphing over other people. As Amory says at one point,
"That competitive instinct only wants a badge. If the size of their house is the badge they'll sweat their heads off for that. If it's only a blue ribbon, I damn near believe they'll work just as hard. They have in other ages." (2.5.171)
In other words, human beings will always want something to show that they're better than others. It doesn't need to be money. It can be a nice car, a big house, or a little blue ribbon for all people care—as long as the whole world knows how great they are. Hmm. It sounds like uber-competitive (and penniless) Amory might be projecting a little bit.