Exactly, and you need to start turning a profit before the end of that runway. Even if that means running code that is suboptimal.

This reasoning is largely centered around the runway being finite. You obviously can't have costs so high you are making a huge loss, but also there's little value in improving margins past profitability until you actually have a stable segment of the market.

we are all perfectly smooth, round, and filled with an incompressible liquid

Every startup is one bet in a Martingale strategy played by the class of people who remain solvent when you bust.