The Internet is unprecedented in its ability to create infinite markets that are equally sustainable. I coined a new phrase the other day and thought it fits what's happening to a lot of companies. Imagine that you start a business, and you build the biggest thing you can imagine. I've experienced this twice. It's very painful, and you either go bust or lose a lot of money fixing it.
Scale is something that is manageable and that has efficiencies built into it.
Big is not necessarily efficient. For each additional customer we get, our product becomes more compelling, and the ability of others to compete against it decreases. EBay is the greatest example of network effects. That site is almost impossible to dethrone, because all its customers, buyers, and sellers are in the United States. The Internet is a magical box that makes teeny companies look enormous.