I can easily let things that are not working for me go

Two hundred pages into a novel you are not enjoying, the reason for continuing is the two hundred pages. That is the whole argument. The remaining three hundred get read to justify a decision made in a shop in March.

Sunk cost isn't stupidity, it is loyalty pointed at the wrong object — being faithful to a past version of yourself who chose this in good faith with less information.

Letting go gets easier when it stops being framed as waste. Putting the book down is not the loss of two hundred pages. It is the recovery of the three hundred you hadn't lost yet.