This document discusses how network operator costs and revenues are connected through a "ladder" of causal relationships. It explains that revenue comes from delivering good quality experiences to users, which requires sufficient network capacity and flows without excessive packet loss or delay. Costs arise from the physical infrastructure and active network mechanisms needed to support these flows. Multiplexing plays a key role by matching variable demand to fixed network resources, but introduces risks of packet loss and delay if not performed effectively. Predicting and controlling these multiplexing effects is important for maximizing profits while managing costs and risks.