I just read this in a post about learning to be an entrepreneur:
Paul Graham promotes the view that it’s a bad idea to begin with big ambitions, because the bigger they are, the longer they are going to take to realize, and the longer you are projecting into the future, then the more likely you are going to be wrong. “The way to do really big things,” he says, “is to do really small things, and grow them bigger.”
This important advice is often difficult to get across because it can sound unambitious, but that misses the point. The safest way to get big is to build momentum by getting early scores on the doors. Success begets success and the business model gets validated with less time and money.