There's a pretty noticeable difference between someone doing something for their own sake and someone doing something for the sake of another. Compare two pretty universal experiences: "Talking to someone who is only interacting with you because they want something" and "Being the recipient of a no-strings-attached favor".

This attitude is universal; it's not specific to business. Everyone has wants and goals, not just business people. What you imagine my life situation to be isn't really very relevant. Unless you live in a solitary confinement, this is applicable to you.