How to differentiate between gross profit margin expenses and net profit margin expenses?

Let’s say your cost basis for a product is $9. You sell said product for $27. In this very simplistic example, your gross profit margin and net profit margin would amount to 66%.Now, I understand that basic employee payroll and accounting/legal fees are not to be accounted for within the gross profit margin.But let’s say that in order to purchase said product, you have to convert currencies. You’ll be losing a bit of your money’s value having to convert it each time. Or perhaps you can only purchase this product using crypto. Now you have to also take into account the conversion rates AND the respective exchange’s flat rate fees.Let’s also say that when you sell the product, your payment processor takes 3%. And the platform that you sell on takes an additional 2%.Would all of these expenses be filed under a gross profit margin or a net profit margin? At which point do the expenses rl over into the “net” side of things? see hubwealthy.com/wealthy