Sunk cost fallacy

You bought the ticket, you got food poisoning, you go anyway and feel awful. The money is gone either way.

Definition

The tendency to continue an endeavour once an investment in money, effort, or time has been made, even when continuing is irrational.

Step 1

Predict first

In one or two sentences, what do you think this concept means? Wrong is fine; the small struggle is what makes the answer stick.