Fully synthetic human insulin gets cheaper to make year by year, so the profit goes to the delivery tiers in various ways, with most of it going to the Pharma companies who operate as a price managing cartel - quite illegal in the USA. In other global areas the prices are far-far cheaper, such as third world area - whose people would die unmedicated if forced to pay US prices. The whole FDA approval/regulation process is responsible for this under the guise of safety coupled with IP 'protections' (these freshly issue IP protected variants [every few years] they keep the game going.