How do you test whether an idea is worth building?
Run a two-week validation sprint before writing a single line of code. Talk to ten target users, offer to solve their problem manually, and see if anyone will pay, commit time, or refer a friend. If nobody moves, the idea is not the problem - the demand is. Validation is not a survey; it is watching what people actually do when the friction is real.
Source: Framework: The Validation Sprint, from Dr. Malak's From Idea to Innovation keynote.