I’ve heard this truism my whole life, and glibly repeated it myself at least a few times. But we must acknowledge that it expresses a morally defeatist attitude (cynicism) that poisons the person who actually lives by it.

The truism is usually deployed right after someone’s good deed was taken advantage of, but the correct solution is not to avoid being good to others, as the truism suggests. It is simply to make sure you’re being good to yourself as well.

For example, someone you don’t know asks to borrow your car to pick up their kid from school. Being good to them is helping them pick up their kid. Being good to yourself is driving them there yourself instead of handing a rando the keys to your car.