Sunk cost fallacy

Continuing with a course of action because of what has already been spent, when the spending cannot be recovered and should not affect the decision.

It appears in portfolios as averaging down on a position because of the loss already taken, and in companies as continuing to fund a project because of the capital already committed.

The correct question ignores history entirely: given everything known now, is this the best use of the next rupee?

What is spent is gone. It is not an argument.