I think this boils down to a more general rule. If you are going to start a business about anything, you should know what that “anything” is in fairly great detail. To think you can start a business and not have much of an idea about the details of the product or service on which the business will be based on, is a surefire sign failure about to happen.
One more important thing an Entrepreneur must have than the details of the “anything” is an insatiable desire to learn new things. Because, despite knowing the details about that “anything”, there is soooo much more to know about running a business and producing that “anything” with any type of quality. It starts with finance and goes to managing and leading people, to systems, to production, to service orientation and a whole lot more. You must be open and super curious to learn all the time. Especially when things don’t go as well or expected as you think. That’s when you learn the most and you can be 100% certain, nothing will go as you dreamt it would. Nothing!