Pippa gets stranded in the woods with a flat tire.
A random stranger stops, changes her tire for her, refuses to take her money, and leaves.
Pippa: People only do charity for selfish reasons.
Selfishness is a good explanation for a lot of ways people interact, but if you take it to Ayn Rand extremes where everything everyone does is selfish, you're being edgy to the point of silliness.