In a perfect market, the marginal cost of a digital (online) product is zero. This means that the price of a digital product tends to zero: welcome freemium and ad-supported business. However, only firms with network effects dominate and benefit. The core reason is that if in a perfect market, and the marginal cost of producing digital product is zero, the price will inevitably go to zero.
This is the heart of the freemium model where you get many things free, which is possible because of the aggregation construct, where companies provide those digital products and then create an ecosystem to sell adverts. The firms benefit more than the suppliers by providing the platforms [Facebook makes money for photos supplied by families. Sure you like the Likes]. As shown in the Figure, great companies deliver the near-zero marginal price for high quality product, making it challenging for anyone that carries a non-zero marginal price to compete, exacerbated if the product is even not top-grade. This is one of the biggest challenges digital entrepreneurs face.