Sunk costs refer to the money or resources that have already been spent and cannot be recovered. These costs should not be considered when making decisions because they are already gone and cannot affect future outcomes. Full definition
Right there, buried in all the cruft, are good and sensible posts (1, 2, 3, 4, 5) which are not only grounded in reality, but which also stray from the normalcy of Sunk Cost Fallacy and Cognitive Dissonance. (dereksmart.com)
In one online study, American participants reported about how much they typically focus on the present moment, and also read 10 sunk - cost scenarios — such as whether to attend a music festival that had been paid for when illness and bad weather made enjoyment unlikely — and then reported how much they would let go of sunk costs in each of them. (sciencedaily.com)