For a project to generate revenue in a predictable way you need at least a few customers. I say at least a few because you can invent something and even without any customers (or users) sell that invention.
In this case, I'm talking of the more general term of a product or service that generates revenue. If you only have on customer it kinda fits the description but I think more of it as a contractor or outsourcing.
The baseline is you have to have some customers. But, to have customers you need a group of people willing to try it. Why should they learn about your product and try it?
That's the question. Why it matters and to whom?
Someone needs a positive, welcomed or necessary outcome. This outcome has to be recognized and wanted. If a person doesn't want or see the benefit of quitting smoking a product that's helps quitting is worthless.
Validation gets so much attention and deservedly. Especially if you want to bootstrap a business. Validation is searching or confirming that a certain audience recognizes and wants a specific outcome.
Your product will help achieve that outcome.
From the basics of a revenue generating project post.