A key early metric, "negative churn," showed that initial users not only stayed with Uber but also increased their usage over time. This powerful data demonstrated deep product-market fit and signaled massive potential for future growth, helping attract significant venture capital.

Vanity metrics like total revenue can be misleading. A startup might acquire many low-priced, low-usage customers without solving a core problem. Deep, consistent user engagement statistics are a much stronger indicator of genuine, 'found' demand than top-line numbers alone.

The founder realized he had product-market fit not from praise, but from anger. When the system went down, his few early customers were furious because they had come to rely on it, even in its imperfect state. This is a powerful, non-obvious signal of true customer dependency.

When facing constant rejection from investors, the ultimate test of whether a founder's vision is ambitious or delusional is customer behavior. Despite being a non-consensus bet for years, DoorDash persevered because metrics like customer retention proved people genuinely wanted the product.

Since today's AI companies grow too fast to have multi-year renewal data, investors must adapt their diligence. The focus shifts from long-term retention to short-cycle retention and, crucially, deep product engagement. High usage is the best leading indicator of future stickiness and value.

When business metrics are flat, motivation can be sustained by chipping away at a genuinely hard technical problem that the founder finds satisfying. Tela's team stayed motivated during slow years by focusing on solving difficult rendering bugs, a challenge they were passionate about, which ultimately unlocked growth.

Despite selling to eight law firms at its first conference, Filevine experienced a brutal eight-month period with virtually no new customers. This highlights that early traction can be misleading and founders must endure long periods of zero growth before finding a working GTM motion.

Instead of focusing on traditional sales metrics, one company found its most powerful leading indicator for organic growth was the volume and quality of conversations between its own engineers and its customers' engineers. This metric became the central focus for driving the business forward.

While "scratching your own itch" is common advice, Filevine's founder found it amplified the frustration of early struggles. He had built a product for his own law firm's problems and knew thousands of similar firms existed, making their rejection of his solution particularly demoralizing and confusing.