Sunk Cost Fallacy

mental-model

The sunk cost fallacy is letting an irrecoverable past investment control the next investment. A sound decision ignores what has already been spent and asks whether another unit of time, money, or attention is worthwhile now.

Finishing a book can be a waste of reading time. Once you discover that it is a dud, the pages already completed are not a reason to sacrifice the hours still available to you.

The past makes a claim on the future

Investment creates a false sense of obligation: abandoning the book, project, or purchase seems to waste what you put into it. But that cost has already been paid and cannot be recovered by spending more. The actual choice is between the value of continuing from this moment and the value of the best available alternative—an opportunity cost that disappears from view when you keep staring backward. Loss Aversion helps make quitting feel like admitting a loss, even when continuing only enlarges it.

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Where it shows up

The unfinished book

If a book no longer rewards your attention, quitting frees the remaining hours for one that might. Completion does not redeem the time already spent.

The next rupee

For any ongoing expense, erase the historical total from the decision and ask: how much more must I spend from today, and is that additional amount worth it?

Not every difficult middle is a sunk cost

Past spending should not dictate the decision, but neither does discomfort prove that quitting is wise. The model applies when the argument for continuing is merely “I have already invested so much.” If future benefits still justify future costs, continuing can remain the better choice.

Price only the remainder

Choose one commitment you are reluctant to abandon. Write down only what it will cost from today onward and what that remaining investment is expected to deliver. Continue only if you would knowingly buy that remainder at that price now.

Episodes that teach this

Finishing Every Book is a Waste of Time - 6 Hacks to Read More, Better, Faster - Future IQ 30,154 views
If a book does not spark joy, quit it; sticking with a dud because you started it is described as the sunk cost fallacy.
Sunk Cost Fallacy, Loss Aversion and Endowment Effect Explained with Examples · explained at 3:48 5,429 views
"Forget how much you spent so far... from today onwards how much extra do you have to spend and is it worth it?"