When you are creating a demo, there is the constant temptation to add more features. You need to resist this temptation.
A demo is not a product. It’s a promise that there could be a product, which is a very different thing.
A product needs an undo option, a way to connect to a database, compatibility with various file formats, and many other things besides. That takes time and money.
What the demo does is explain why that time and money should be expended. It is, more than anything else, a form of storytelling.
Building a aemo building and building a product are two very different endeavors. They are complementary yet quite different parts of a larger process. It is important not to confuse the one with the other.