No. Increments in outgoing liquidity (plus on-chain funds) - assuming that you do not add/remove funds yourself. Your earned fees may actually increase at the same time as your outgoing liquidity decreases. This situation may arise during circular payments, for instance - perhaps depending on implementation and circular payment method. I've run a lightning node for some time, and while I have accumulated fees I definitely operate it at a loss. My motivation for running it is however not to be profitable (in sat terms).