Rabois introduces a nuanced framework beyond just product-market fit. He argues that exceptional marketing can create a temporary illusion of success, but this "marketing fit" will eventually collapse if the underlying product value isn't there to retain users.

Founders often try to convince themselves they have PMF. The actual moment of achieving it feels like a sudden, unmistakable change—a switch, not a spectrum—making it clear that all previous feelings were just wishful thinking.

Intense early customer love from a small, specific niche can be a false signal for product-market fit. Founders must distinguish between true market pull and strong fit within an unscalable sub-market before they saturate their initial user base and growth stalls.

Many founders mistakenly believe achieving product-market fit is the final step to explosive growth. However, growth only ignites after also finding a repeatable go-to-market fit, which translates the founder's initial sales success into a scalable process that a sales team can execute consistently.

Product-market fit isn't just growth; it's an extreme market pull where customers buy your product despite its imperfections. The ultimate signal is when deals close quickly and repeatedly, with users happily ignoring missing features because the core value proposition is so urgent and compelling.

Initially, customers often "round down," focusing on missing features. A key sign of product-market fit is when they start "rounding up"—their faces light up in demos, and they imagine the product's future potential, forgiving current limitations because they believe in the core value.

Many marketing failures aren't the marketer's fault, but a result of joining a company that lacks true product-market fit. Marketers excel at scaling demand for something with proven value, not creating demand for a vague idea. It's crucial to verify PMF before accepting a role.

Having paying customers doesn't automatically mean you have strong product-market fit. The founder warns against this self-deception, describing their early traction as a "partial vacuum"—good enough to survive, but not to thrive. Being "ruthlessly honest" about this gap is critical for making necessary, company-defining pivots.

The unambiguous signal of Product-Market Fit (PMF) isn't a magic number in your analytics. It's when customer pull becomes so strong that it breaks your supply chain, logistics, and team capacity, forcing uncontrollable growth even without marketing spend.