Founders mistakenly treat their product idea as fixed while searching for customers. The correct mindset is the reverse: customer needs are a fixed reality. Your product is the variable you must shape to fit that reality, not the other way around.
When a startup finally uncovers true customer demand, their existing product, built on assumptions, is often the wrong shape. The most common pattern is for these startups to burn down their initial codebase and rebuild from scratch to perfectly fit the newly discovered demand.
Innovation isn't random. Pampers' wetness indicator solves a clear problem: parents need to know if a diaper is wet, but the existing option (taking it off) is inefficient. By identifying this unavoidable task and its bad workaround, the exact shape for a winning new feature becomes clear.
A potential customer can logically agree with your framing of their problem yet have no intent to buy. True demand isn't intellectual agreement; it's a palpable force. You must sense the pressure of them actively pushing against a wall. A customer leaning back and nodding is a red flag.
Startups with noble, future-oriented visions often fail by trying to sell the vision itself. Success requires finding a tangible, immediate "attack vector." Tesla's vision was clean energy, but its first product solved the demand from wealthy buyers wanting a high-status alternative to the Prius.
Using a child's toy analogy, demand is a pre-existing hole (e.g., a star shape) and your product is the block. Founders fail when they build a block and then search for a hole it fits. The real job is to first deeply understand the shape of the hole, then craft a block that fits it perfectly.