1. The prize: retention is where the money is
HBR presents this as a synthesis of multiple studies, not one experiment. The flat "5x" version has a fuzzy origin — attribute as a widely-accepted range.
The business case for listening to customers has always rested on retention economics. The most-cited version: acquiring a new customer costs far more than keeping one — Harvard Business Review puts the range at five to twenty-five times, framed explicitly as a synthesis of studies rather than one controlled experiment.
The companion figure comes from Bain's Frederick Reichheld: increasing retention by five percent can lift profits by 25% to 95%. It is genuinely attributable to Bain — but the underlying research traces back to a 1990 HBR paper, and the range is a cross-industry generalisation, not a single measurement. Cited honestly, it still makes the point: small retention gains compound into large profit gains, which is exactly why understanding why customers leave is worth doing well.