Sunk Costs and decision making

If you bought a movie for $20, and after 20 mins, you realize that it’s gonna be a terrible movie. Would you leave or stay?

If you stuck with a question for 10 mins, would you start the new questions and go back to it once you’re done or would you keep tackling the question?

A decision should be made without sunk costs consideration.

Same with relationships when you spend time and money on the girl but it leaves only a slim chance for you two to get together.

Same with stocks when you realize that you start losing.