Answer: Sunk cost fallacy
Explanation: From the context above, The argument highlights an example of 'a sunk cost fallacy' which usually arises when individuals or group are about to make future financial decisions on a project and they make reference to sunk or retrospective cost. The sunk cost is that expense which has been spent or incurred on a property or project in the past. The sunk cost fallacy is highlighted in the argument of parents who object future decision based on sunk cost incurred which are no longer recoverable.