I would think that if all your markup goes to warehouse and employees (operating costs) and the membership is all "pure profit", there's not a lot of money left

I would think that if all your markup goes to warehouse and employees (operating costs) and the membership is all "pure profit", there's not a lot of money left over for R&D or tech upgrades without hurting your own margin. At least if you take the article at face value in the simplicity of it's explanation. I imagine it's more complex than that