I'm somewhat amazed that you are truly unconvinced that most people are self-serving in their mental formulations. What a wonderful environment you must abide in to have avoided frequent exposure to these common foibles. On this score we simply will not agree, I fear. But your citation of the field of ethics to buttress your own view rather clearly points out the problem. Most people have no grasp of the field, or even the meaning of the word. The are as insensible of the field and its significance as they are incapable of any exegesis of libertarianism.

On that matter, I’d argue that if your goal is to avoid rationalization - libertarianism as an ideology actually makes one tend to rationalize less

You're going to continue to propose, I'm sure, that most of those who claim to espouse the philosophy actually do espouse it, or even know it as an academic might. As if after selecting a value system that rewards their own enshrining of their self-interest they will then in good faith take equally to heart the elements of the ideology that challenge them.

This conversation is going to go nowhere. You want to debate the actual principles of the ideology, and I think what the rapacious espousers of the ideology have in common is their rapaciousness, and that is the most salient feature that distinguishes the ideology in the world of results and not theories.