sunk cost fallacy
noun[S]
ECONOMICS,MANAGEMENTukustheideathat acompanyororganizationis morelikelytocontinuewith aprojectif they have alreadyinvesteda lot ofmoney,time, oreffortin it,evenwhencontinuingis not thebestthing to do:
Economists wouldpointout that thesunkcostfallacyisirrational, and could bedescribedas "throwinggoodmoneyafterbad".
See also
Concorde fallacy