Sunk Cost Fallacy

Sunk Cost Fallacy

WHY YOU SHOULD FORGET THE PAST
The sunk cost fallacy is most dangerous when we have invested a lot of time, money, energy or love in something. This investment becomes a reason to carry on, even if we are dealing with a lost cause. The more we invest, the greater the sunk costs are, and the greater the urge to continue becomes.

Investors frequently fall victim to the sunk cost fallacy. Often they base their trading decisions on acquisition prices. ‘I lost so much money with this stock, I can’t sell it now,’ they say. This is irrational. The acquisition price should play no role. What counts is the stock’s future performance (and the future performance of alternative investments). Ironically, the more money a share loses, the more investors tend to stick by it.
This irrational behaviour is driven by a need for consistency. After all, consistency signifies credibility. We find contradictions abominable. If we decide to cancel a project halfway through, we create a contradiction: we admit that we once thought differently. Carrying on with a meaningless project delays this painful realisation and keeps up appearances.
Of course, there may be good reasons to continue investing in something to finalise it. But beware of doing so for the wrong reasons, such as to justify nonrecoverable investments. Rational decision-making requires you to forget about the costs incurred to date. No matter how much you have already invested, only your assessment of the future costs and benefits counts.

 
The Art of Thinking Clearly

Rolf Dobelli

 

Image: ‘Ace of Spades’ by Richard Swain | https://www.flickr.com/photos/128562165@N06/16614850351/in/photostream/



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