Quint is a fisherman stereotype, but he also represents the inclination to greed which the people of Amity Island are also guilty of. Money is more important than life, in this case even his own. He is willing to take unnecessary risks to get the reward, he even breaks the radio on his boat to not have any help (so as not to share), and in the end he pays with his life.
Quint is even an archetype very much similar to Captain Ahab in Herman Melville's Moby Dick, only he is hunting a great white shark instead of a whale. In this respect, he takes on a role "bigger than life" and dies as a hero.