·Psychology & Behavior
Section 1
The Core Idea
Sunk cost fallacy in action: doubling down on failing projects to justify past investment. Barry Staw's 1976 study gave MBA students the role of a financial VP allocating R&D funds between two divisions. After the first round, they received performance data showing one division had failed. The rational response is to shift resources to the performing division. The actual response: students who had made the original allocation to the failing division invested significantly more in it the second time. They escalated. Students who inherited someone else's failing allocation did not — they cut it. Same data. Same decision. The difference was personal responsibility. The person who made the original bad bet doubled down to justify it.
Vietnam. Concorde. Countless corporate projects. The pattern repeats at every scale. The Vietnam War is escalation of commitment played out across a decade and 58,000 American lives. Each troop increase was justified by the prior troop increase — withdrawal would have meant the previous soldiers died for nothing, so more soldiers were sent to make the previous sacrifice meaningful. The logic is circular and self-reinforcing: the worse the outcome, the greater the investment required to justify the prior investment.
By the mid-1970s, both the British and French governments knew the supersonic jet would never be commercially viable. The development costs had ballooned past every estimate. The economic case for cancellation was overwhelming. The political case for continuation was stronger: billions had already been spent, national prestige was at stake, and no politician wanted to be the one who admitted the programme was a mistake. They kept funding it. The plane flew for 27 years. It never turned a profit. Economists call sunk-cost-driven escalation "the Concorde fallacy." Yahoo acquired Tumblr for $1.1 billion in 2013. Within two years, the platform was declining by every metric that mattered — user engagement, advertiser interest, cultural relevance. Yahoo's response was not to write down the acquisition and redeploy the capital. It was to invest further in Tumblr's "turnaround." By 2019, Verizon (which had acquired Yahoo) sold Tumblr to Automattic for roughly $3 million. The $1.1 billion was gone. Years of management attention was gone. The opportunity cost of what Yahoo could have built with those resources was incalculable.
The mechanism combines three psychological forces that compound destructively. First, the sunk cost fallacy: past investment feels like it will be "wasted" if the project is abandoned, even though the investment is irrecoverable regardless of the decision. Second, ego protection: the decision-maker's identity is fused with the decision. Killing the project means admitting the original decision was wrong. Third, commitment and consistency: people who have publicly committed to a course of action will go to extraordinary lengths to remain consistent — even when the evidence has invalidated it.
Amazon's "two-way door" — reversible decisions don't trigger escalation. Bezos: "If you're not stubborn, you'll give up on experiments too soon. If you're not flexible, you'll pound your head against the wall." The distinction: stubbornness on the right bets, flexibility on the wrong ones. The antidote is structural, not psychological. Pre-commit exit criteria before investing more. The person who made the bet cannot objectively evaluate whether to continue it. Staw proved this in 1976. Fifty years of research has confirmed it.
The most dangerous feature of irrational escalation is that it masquerades as virtue. Persistence, determination, grit, commitment — the qualities that every leadership book celebrates are the same qualities that escalation exploits. The founder who "never gives up" is heroic when the persistence pays off and delusional when it doesn't. The difference between the two is visible only in the outcome. Without structural safeguards — exit criteria defined in advance, evaluation by someone without ego in the outcome — persistence and escalation are indistinguishable until it's too late.
