Do Not Build

You get a few real attempts at building a company. Pick the wrong market and you burn a year finding out. Do Not Build measures the field before you commit: who's already there, what a customer costs, what it couldn't measure, and the founders circling the same market. So the year goes on a choice, not a guess — and if it works, it becomes a company instead of a lesson. The verdict is where you start, not the decision. 245 screened, 64 cautions at the build line.