Had Alexander Graham Bell lived on a small island with a population of 10, he'd have had little to gain from inventing the telephone. Fortunately Bell introduced his invention into a time with millions of potential customers, spread out on a continental scale. In the 1990s, of course, many new products enter a market of hundreds of millions of customers. Said another way, Thomas R. Malthus had it exactly backward when he predicted that Earth's population would outstrip its resources, leading to ever-growing poverty. There is no guarantee of avoiding Malthus' dismal scenario in anything other than a market-based system.
Population is only one way markets grow.
Rising incomes add to the number of people who can afford to splurge on the latest bells and whistles. Falling transportation costs and quickening information flows can enlarge markets. The dismantling of trade barriers can open whole new markets to U.S. producers. For many products yet to come, the market will be global, so the rewards for successful innovation figure to be even greater.