Sunk Cost Fallacy

We irrationally continue investing in something because of past investments of time, money, or effort — rather than evaluating future value objectively.

• Finishing a terrible movie because you already paid for the ticket.
• Continuing a failing business for years because of the time already invested — instead of cutting losses.
• The Concorde project: governments continued pouring money into it long after it was clear it would never be commercially viable, purely to justify previous spending.