Why I am not a vegan

[Monica]

I must be screwed then because I've often done such acts for the sake of finding greater joy and depth in my life. I thought service to others was service to all? Should such a person then refrain from doing such things?

I think you missed the part about at the exclusion of others. It's fine, even normal and natural, to get joy from helping others! Because yes, helping others helps the ALL, thus helping self as well.

It is only STS if the person doesn't care about other-selves and does it purely for self; ie. only for self. Do you see the difference?

Win-Win is ok, STO. Consciously doing a Win-Lose (when self wins at the expense of others losing) that is STS. You don't have to lose in order to help others. Just don't hurt them in order to help self, and when helping them, if you get helped too, that's ok.