In the novel, young Vito begins his "man of respect" years by achieving a monopoly in the olive oil business. He makes war on other olive oil wholesalers to force them to come to terms with him. The novel doesn't say that his compedtitors are Mafiosi. In fact, the only one of Vito's competitors who is actually killed is characterized as "an arrogant Milanese," scarcely the description of a Mafia guy.