Flanked by a Ferrari, a Maserati, a Bentley, a Rolls-Royce and a Lamborghini, Dallin Larsen paced the stage, swigging deeply from a bottle in his hand. The object of hope was not God but a dark purple fruit juice called MonaVie. Instead, the Utah-based company tore a page from the Avon lady, enlisting regular people to sell the product to friends and family. Now MonaVie claims to be one of the world’s fastest-growing private companies, with inroads on five continents, and an army of drinkers and sales apostles signing up at a rate of 10, a week. As a private organization, MonaVie isn’t required to publish financial data, making such claims difficult to judge. In a sliding economy, MonaVie appears to buck the trend, minting dozens of mom-and-pop millionaires, according to company sales data, and luring customers who rave about the not-too-sweet taste and miraculous health benefits.