4.2 Is the Golden Rule based solely on self-interest?

1) Mysterious Morality Series. This video builds on 4.1 (Ethical Egoism, Morality, and Self-Interest). I have found that many people believe the Golden Rule is based entirely on self-interest, which seems mistaken.
2) My website: lucidphilosophy.com
3) Here is my affiliate link to a strong analytical introduction to ethics:

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