[TonyLima]

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Under certain circumstances it can be quite rational to decline to proceed with such a course of action. For example, it might not be wise to proceed if realizing the greater benefits required bearing accompanying smaller but substantial costs that exceed some threshhold of acceptability. It's one thing if there are 99 units of benefit and 1 unit of cost, and quite another if there are 50.5 units of benefit and 49.5 units of cost. Other factors that could merit reconsideration of a course of action with a 'favorable benefit-cost analysis' include an inequitable its distribution of its costs, and whether they are practically reversible. Maybe there are other factors that, if applicable, could reasonably trump a favorable benefit-cost analysis.

You are not measuring cost correctly. Cost is the total spending plus non-monetary opportunity costs. Also, where is risk?

[TonyLima]

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Under certain circumstances it can be quite rational to decline to proceed with such a course of action. For example, it might not be wise to proceed if realizing the greater benefits required bearing accompanying smaller but substantial costs that exceed some threshhold of acceptability. It's one thing if there are 99 units of benefit and 1 unit of cost, and quite another if there are 50.5 units of benefit and 49.5 units of cost. Other factors that could merit reconsideration of a course of action with a 'favorable benefit-cost analysis' include an inequitable its distribution of its costs, and whether they are practically reversible. Maybe there are other factors that, if applicable, could reasonably trump a favorable benefit-cost analysis.

You are not measuring cost correctly. Cost is the total spending plus non-monetary opportunity costs. Also, where is risk?