What is the theme in Master of the Game by Sidney Sheldon?

Ambition is the main theme in the story. Jamie McGregor is determined to be a rich man. Jamie gives up his shares in his family farm to travel halfway across the world to South Africa in order to search for diamonds. Jamie is young, naïve, and he believes the world is his for the taking. Jamie learns quickly, however, that he cannot trust anyone but himself. Jamie enters into a contract with the owner of a local store and is cheated.