For so many startups and even larger tech incumbents, the point at which they hit the shoulder in the S-curve is a mystery, and the author suspects the failure to see it occurs much earlier. The good thing is that identifying the enemy sooner allows you to address it. We focus so much on product-market fit, but once companies have achieved some semblance of it, most should spend much more time on the problem of product-market unfit. In strategic planning, the question in building a forecast is to flush out what the author calls the invisible asymptote: a ceiling that our growth curve would bump its head against if we continued down our current path. It's an important concept to understand for many people in a company, whether a CEO, a product person, or a planner in finance.