It doesn’t matter if you want to dance at your friend’s wedding; if you think the wedding would be “better” if more people danced, and you dancing would meaningfully contribute to others being more likely to dance, you should be dancing. You should incorporate the positive externality of the social contagion effect of your actions for most things you do (eg if should you drink alcohol, bike, use Twitter etc.).
Yes! I wish more people adopted FDT/UDT style decision theory. We already (to some extent, and not deliberately) borrow wisdom from timeless decision theories (i.e. “treat others like you would like them to treat you”, “if everybody thought like that the world would be on fire” etc.), but not for the small scale low stakes social situations, and this exactly the point you bring here.
Yes! I wish more people adopted FDT/UDT style decision theory. We already (to some extent, and not deliberately) borrow wisdom from timeless decision theories (i.e. “treat others like you would like them to treat you”, “if everybody thought like that the world would be on fire” etc.), but not for the small scale low stakes social situations, and this exactly the point you bring here.