“I can’t leave now. I’ve already spent twenty years building this career.” If you’ve ever caught yourself thinking this, you may have encountered one of the most powerful biases in human decision making: the sunk cost bias.
Decades of psychological research have established that we are not the rational decision makers we tend to believe we are. Our choices are shaped by systematic patterns of biased reasoning, and nowhere is this more consequential than in major life decisions.
The sunk cost bias refers to the tendency to keep investing in something, even when it is no longer beneficial, simply because of how much you have already put in. Time, money, effort, identity. People influenced by this bias persist with an option not because it serves their future, but because abandoning it feels like losing everything they have already spent.
This is a very powerful bias when people are considering a transition in their personal or professional life. I experienced this myself when I was considering leaving academia: “Wait, leaving academia? Twenty years of building a career, a professional network, all the sacrifices. Gone?”
Why the sunk cost bias is an error
From a decision-making perspective, this tendency is considered an error, which is why it is often referred to as the sunk cost fallacy. Past investments are gone regardless of what you decide next. The rational question is not how much you have spent, but what the future value of continuing actually is.
This was demonstrated clearly in experiments by psychologist Jonell Strough and colleagues, who showed that participants who had paid for a cinema ticket were significantly more likely to sit through a boring film than those who had not paid. The investment had no bearing on whether the film was worth watching. But it powerfully shaped the decision to stay.
You might reasonably object that a cinema ticket is trivial compared to twenty years in a career or a long marriage. That objection is supported by the research: the sunk cost effect grows stronger as the size of the investment increases. Psychologists call this commitment escalation, the tendency to continue an endeavour precisely because so much has already been invested in it. But the underlying error is the same. You are weighing your future based on time and energy already spent, rather than on the value of what lies ahead.
Why some people are more vulnerable than others
Several psychological mechanisms drive the sunk cost bias. One is loss aversion: the pain of losing a prior investment tends to feel more powerful than the potential benefit of change. Another is waste aversion, a strong aversion to the thought of wasting resources (time, money, efforts). There is also the discomfort of admitting that an earlier decision may have been wrong, which may lead people to continue investing in a failing project to justify their earlier decisions. This may be prevalent in people in leadership and managerial roles, or in people who fear the judgement of others or hold themselves to high standards of consistency.
What the research reveals, and what I find particularly relevant for the high-achieving professionals I work with, is that the traits that tend to make people successful can also make them more vulnerable to this bias.
Psychologist Markus Domeier and colleagues found that people preferred to keep investing in low-return options—therefore showing a sunk-cost effect—when doing so maintained their sense of competence. If you have spent years building expertise in a field, that competence becomes part of the investment you consider leaving. The bias is not just about time or money. It is also about identity.
High conscientiousness, characterised by reliability, discipline, and a strong sense of obligation, also increases susceptibility to the sunk-cost bias. People with high conscientiousness often feel a moral duty to honour the years of training and effort they have invested. The years can begin to feel like an active asset when, in economic terms, they are already spent—they are a sunk cost.
If you recognise these traits in yourself and you feel stuck at a crossroads, it is worth asking whether you may be influenced by the sunk-cost bias. You may find that the investment you are most reluctant to abandon is one that no longer holds value for your future.
What neuroscience tells us
Neuroscientists Haller and Schwabe showed that when people make decisions based on prior investments rather than current circumstances, activity in the ventromedial prefrontal cortex, a brain region central to evaluating the future value of options, is reduced. These findings suggest that prior investments can influence the neural systems involved in the processing of future decision alternatives. Additionally, individuals with a particularly strong aversion to wasting resources showed higher activation of the dorsolateral prefrontal cortex, which in turn suppressed the activation of the ventromedial prefrontal cortex. Suggesting that certain psychological tendencies, such as a psychological aversion to waste, can alter the neural processes involved in evaluating our options.
How to recognise and loosen the bias
Recognising the sunk cost fallacy does not mean that leaving is always the right decision. It means making sure that your decision is guided by the opportunities and costs that lie ahead, rather than by investments that belong to the past.
Awareness is the starting point. If you find yourself returning repeatedly to how much you have already invested, rather than to what your current circumstances are actually offering you, that pattern is worth examining.
The more useful reframe is this: past investments are rarely lost in the way the bias suggests. They are transformed into skills, judgement, relationships and ways of thinking that move with you into whatever comes next. A long career does not disappear when you change direction. It becomes a foundation. I would have never been able to establish a successful business in coaching and consultancy if academia did not teach me to critically analyse, spot hidden patterns in chaos, and the beauty of experimenting.
I use an exercise with clients I call the Asset Portability exercise, which makes this tangible. Start by listing the five most significant skills, personal attributes, or insights you have gained across your years in your current field. These can be professional, such as analytical precision, specialist knowledge, or the ability to manage complexity, or personal, such as the resilience built through difficulty, the relationships you have formed, or the discipline developed over years of sustained effort. For each one, ask yourself a single question: does this asset belong to my current role, or does it belong to me? In most cases, the answer is the latter. The expertise, the judgment, the experience: none of it disappears when you leave. It moves with you. You are not starting from scratch. You are starting with an inventory of proven value that no change can take away.
Finding yourself stuck in a circle of overthinking?
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About the author
Dr Giulia Galli. An accredited coach, chartered psychologist, and academic neuroscientist with twenty years of experience in understanding people’s thinking, decisions and behaviour. You can read more about my story and my approach to coaching here.
