All Markets Are Not Created Equal (Note to Self on TAM)

'Total Addressable Market' (TAM) is often used as a single big number to justify a startup's potential — 'the market is $50 billion, so we could be huge.' Gurley's point is that the size of the market on paper tells you almost nothing on its own; what matters is the structural quality of that specific market — things like whether the product is used frequently or rarely, whether the marketplace naturally consolidates around one winner, whether there's real network effects, and whether new supply/demand can be added cheaply. Two markets can have the identical dollar-figure TAM and be wildly different investments.