The marginal cost of selling the data is effectively 0, since the difference between selling "zero data" and "one data" is 0, and the difference between "n data

The marginal cost of selling the data is effectively 0, since the difference between selling "zero data" and "one data" is 0, and the difference between "n data" and "n+1 data" is also 0. The sale of data was essentially "free" to the business as a revenue stream, it cost them almost nothing extra to sell the data (again, beyond building a portal and integrations). You CAN discount the cost of data maintenance, from the sale business since the core business (also profitable) is already factoring in the cost. You can't double-count the costs, and accounting DOES let you pick-and-choose where to apply those costs.