Negotiorum gestio only requires behavior, regardless of the consequences. As a manager, I can ask not to pay the necessary management fees. For example, your house is on fire, and I am your neighbor. No one in your house caught fire later. I saw it, so I went to put out the fire. Later, the fire was too big. I tried my best but I still didn't put it out. Finally, your house was burned down. In order to help you put out the fire and burn my arm, you need to pay for my arm treatment.