In a free market, however, the only obstacle faced by new entrants is the need to match the productiveness of the successful companies. Without government-enforced privileges, a firm can dominate a market only by providing better products or lower prices than its rivals. Markets, strategies and technology are never stagnant. No matter how well a given company does at a given point in time, there is no guarantee that it will retain its competitive advantage. Even the top firms can sustain their positions only if they continue to innovate and improve.
Economic power is fundamentally different from political power.
Economic power consists of incentive and reward. It entails voluntary trade. If Microsoft is willing to license its products to computer manufacturers on the condition that they not feature Netscape's product, that is a trade. There is no trade and no choice involved. Political power simply forbids productive activities under the threat of fines or imprisonment.