People are notoriously bad at making assessments on when it’s time to stop. They tend to be influenced by the psychological sense that they might be throwing away their investments. ~ American psychologist Alan Lambert
There is a strong tendency to view time or resources spent as an investment, even when the relevant dynamic has no relation to, or prospect for, reward. Some things simply don’t pay back.
Feeling a “sunk cost” can strongly bias the decision to continue an endeavor, and so risk further loss. The sunk-cost effect reflects emotional attachment. Continuing a gamble, a bad relationship, or a war, is commonly done simply because an “investment” has been made, and to not persist would be a “waste.”
Lives may be one of the more potent triggers of the sunk-cost effect. Money and relationships that are sunk are tough, too, but throwing away lives is deeply aversive, and such a powerful thing. ~ Alan Lambert
Many animals beside humans suffer sunk-cost thinking. Its bias of diligence is not without rationale, and so has been conserved in evolution.
If the correlation between past efforts and future value provides better predictions than the uncertainties of future outcomes, then animals may have evolved processes that use past effort as a proxy to estimate future value. ~ American psychologist Angus MacDonald III et al