Inspiration was involved in creating some of the best things ever created. But there are many examples to show us that the value of these things was not appreciated at the time of their creation, except by the person involved in creating them, a person possessed by inspiration.
When inspiration tells you to create something, there usually is no good logical explanation for the value of what you're creating — or, if there is, it's just that you're a good salesman, and you've made a convincing rationalization for the value of your work-in-progress.
And not all inspired works turn out to be big hits. Not all of them find a place in history books. As the creative artist seized by inspiration, you have no way of knowing if your work will be valuable or not. Inspiration undermined your objective judgment. And there's no one else who can tell you, because no one else fully understands the vision that you see. There simply is no rational way to tell whether you're on a fool's errand or creating a timeless masterpiece.
If people say you're crazy, and that your work is misguided, there's no way to prove them wrong. The best you can do is complete your work, and hope that other people recognize it as something uniquely valuable.
This great level of uncertainty is one of the things that makes the creative life feel stressful and lonely. At times like these, it's good to be connected with a community of artists who understand what it's like to be driven by inspiration, and who can offer encouragement and support.