This means that if you start acting maliciously, or even just not fulfilling your responsibilities (e.g. you let your computer go offline), then you are punished for it (depending on the severity of your offense, obviously).
Aka, you can't just wait for the money to roll in. You have to run a node, you have to verify blocks, and you have to make sure you're acting in the best interest of the network + keeping things running smoothly.