End users use your cool idea. Customers send you money. A design engineer uses your software. The vice president of engineering approves the purchase thereby becoming your customer. Young people watch videos on YouTube.com. Companies advertise on the web site and are your customer.
Customers are attracted by end users who want to use your cool idea. So you must get end users excited, compelled, to use what you are offering. When customers see a large number of end users are eager for your product or service, they will become eager to be your customer (send you money).
This means you need a second forecast. The first is the number of eager end users. The second is the number of eager customers and how much they will pay you. That is how you calculate the size of your market in monetary terms. That is the final definition of SAM (see yesterday's blog).
BOTTOM LINE: Plan on appealing first to end users followed by customers. Create your compelling value proposition for both. Count how many there are of both. Add the price paid per customer and your market forecast is finished. Congratulations, you are building a business plan based on how the real world works. It is a powerful element for building your unfair advantage.