Have you ever use the business model canvas? If you did, you are familiar with the “Customer Segments” section. Usually, when I talk to early stage founders, they don’t have a very clear idea about this section. If you listen to them, they are basically targeting everybody.
Unless you understand extremely well who are your first 10, 100, 1000 customers/users, you will have a hard time scaling your business. People have a hard time selling to the very first customer, but they easily describe how to get from 1 million to 2 million.
While they are most likely wrong about that assumption as well, they fail in delighting their early adopters.