You mean.. mothers breastfeeding feeding their children? You mean men who find big rocks and throw them into water from heights to make a big splash? Do you mean people who donate their organs to other people? Do you mean the many artists, scientists, teachers, and basically everyone else that gets their ass out of bed every day to then put a smile on their face for other people, despite feeling existential despair inside because the last shred of reason for being has been invested in someone or something else, so they keep moving? Robin Williams?
I think we have very different ideas of what self-interest is. Namely, I think that you have confused the idea that one must suffer, or at least feel nothing, or it's not altruistic enough. That one should not enjoy acts of love, kindness, caring, giving, art, exploration... or they're secretly solipsistic. This isn't the condemnation of the world you think it is. This feels like a projection of an internal insecurity onto the greater portion of humanity.
I think most people have been guilty of thinking this at some point. Rather than feel threatened by my words or that I'm being critical of you and only you, I would ask that you do what I did when I once thought this very thought... think on if you're really willing to live the rest of your lived experience with this thought at the forefront. Not everyone gets this one right, but it could have consequences on your ability to actually 'enjoy' another human being without needing something from them to do so.