Moreover, if you are properly-aligned in life, whats good for others/the world is ALSO good for you. Even those who make genuine self-sacrifices would say so - at the very least, NOT having done it would be the real, unbearable, sacrifice.

I really hope you'll reflect deeply on this, and perhaps that it even haunts you - even if just out of pure self-centeredness, since the only people who you would ever have in your life with a mentality like this would necessarily be completely self-centered as well.

People never "do good" "just for the sake of it" - there is always a reason, whether or not the person realizes it. The reason could be, e.g., as I said, the desire to seem good, some kind of religious belief, etc. Ultimately, it is never "just for the sake of it"

I am also disappointed, and I don't know what to do with this, but I am not willing to become some kind of ignorant, delusional lunatic.

Instead of labeling or patronizing them, a bit of tact and compassion go a long way. Otherwise you're just confirming what they're predisposed to think.

It feels nice. You should try it sometime.

Not to mention that wanting approval and recognition is not really “ulterior”. It’s a natural human desire. The people to watch out for are those who claim not to want it.