Clayton Christensen's 1997 book asks why well-managed companies with every advantage lose to inferior entrants.

The puzzle

Christensen studied the disk drive industry, where generations of leaders were displaced repeatedly. The failing firms were not complacent. They had better technology, more capital, deeper customer relationships, and they listened carefully to what their customers asked for.

Sustaining and disruptive

He separates two kinds of innovation. Sustaining innovations improve a product on the dimensions existing customers value, and incumbents nearly always win them, whatever the scale of the technical change.

Disruptive innovations are worse on those dimensions. They are cheaper, simpler, and appeal to customers at the bottom of the market or to people who were not buying at all. For an incumbent, serving that segment means lower margins and unhappy best customers, so declining is the correct decision by every rule the company runs on.

The entrant improves from that position until the product is good enough for the mainstream, at a cost structure the incumbent cannot match. By the time the threat is unambiguous, the response requires a cost base the incumbent does not have.

Why good management is the trap

The mechanism is the argument. Resource allocation follows margins; margins follow existing customers; existing customers do not want the disruptive product until it is too late to respond. Christensen's recommendation is structural: place the disruptive business in a separate unit small enough to be excited by a small market and free of the parent's margin requirements.

The criticism

Jill Lepore argued in 2014 that the case selection was favorable and the predictive record weaker than claimed. Christensen also noted that "disruption" had come to mean any large change, which drains the term. Used precisely, it remains the best account of why incumbents with every advantage lose.