When it comes to making decisions, logic suggests we should only weigh the present options. Yet, our previous investments often influence us.

Consider the time, effort, or money you’ve poured into a venture or relationship. It’s challenging to ignore these "sunk costs." This is why the Flamanville nuclear plant’s completion stretched to 17 years instead of 5, costing sixfold the initial budget.

The sunk cost fallacy is swayed by several psychological factors:

• Positive framing can make us more inclined to continue, even though a negative presentation might be equivalent.
• Optimism bias is common among developers, who often provide overly hopeful timelines to managers and product owners.
• For managers, continuing a costly project can seem sensible to maintain their reputation.
• The reluctance to waste can lead us to endure a mediocre performance simply because we’ve paid for it.

Reflecting on past choices can be enlightening. At times, persisting seems wise. But often, when we finally halt the spending, we realize we could have stopped sooner. In some cases, perseverance leads to success. With each decision, we aim to improve.