Easy.

Now try it at a rural critical access hospital for rattlesnake antivenom with a short shelf life, so it usually expires unused. They are required by law to stock it or they cannot have their emergency room open. Estimate the revenue generated from treating the one patient who needs it every other year, and by the way, you have 9 contracted payers with different rates and you don't know which one, if any, the patient will have. Rinse and repeat for every other drug required to provide "critical care". Maybe layer on infusion of exotic chemotherapy drugs or monoclonal antibodies to treat a new pandemic virus.

It's not easy.