Self-Interest and Morality can and often do co-exist.
It puzzles me that people think they can not. It's a little like when people think drugs should all be illegal because otherwise everybody would be on drugs. I always want to say: "No, it's because you think you would be on drugs". You are basically telling me you are a closet addict.
Your judgements tell the world who you are, not who others are.
So when you think others can not be moral unless they are being forced to work in another person's interest... well... I learn something about you.