Counter lemma: saying "yes" to more opportunities [than one would normally say "yes" to] increases the surface area for happy coincidences (such as meeting the person at the gig) to happen which overall will outweigh the negative effects (annoying the friend and not getting the second invite) in absolute terms.
I.e. I think it's more likely you'll end up in a better place if you say yes more (saying yes to absolutely everything is impractical) rather than just ending up somewhere "different" but equal
Every yes has an opportunity cost. I have had plenty of evenings where more than anything I wished I had just said no and chilled at home with housemates.
I am a big proponent of infinite universes branched at every decision point, and I've no doubt that saying yes every time doesn't result in the happiest outcome possible.
I.e. I think it's more likely you'll end up in a better place if you say yes more (saying yes to absolutely everything is impractical) rather than just ending up somewhere "different" but equal