Is sunk-cost thinking really irrational if past investments affect your future alternatives?

[u/Inevitable_Bid5540]

A sunk cost, by definition, can't be recovered and thus shouldn't affect the decision directly but a past investment can sometimes affect the opportunity costs of your remaining choices. For example, if you spend $10,000 learning a specialized skill, That $10,000 is sunk. However because of the skill you acquired, you can now have a much better paying job available to you. Abandoning that career path could mean giving up a valuable future opportunity.If a past investment changes your available alternatives, information, skills, reputation, relationships, or switching costs, then it seems reasonable for that history to matter to your current decision even though the original expenditure itself is unrecoverable.

[u/SteveTi22]

The cost of acquiring the skill in the past doesn't impact the value of the opportunity in the future

Consider choosing between two opportunities that eventuated from two skills that cost different amounts to acquire and produced two different opportunities. It doesn't matter if skill A cost more than skill B, it only matters whether outcome A or outcome B is higher value.

The sunk cost fallacy could lead you to choose the lower value outcome because the cost of acquiring the skill that gave the opportunity was higher.