So now, you've asserted that this kind of hedonism is objectively worse than some other lifestyle. And my question is, very simply, why? Why is it objectively bad to eat nothing but Twinkies and Yoo-hoo? And the answer I get is that it's bad because it's unhealthy. So then my next question is, why is being healthy objectively better than being unhealthy? And so far, I haven't gotten a coherent answer to that. But that's okay - there really isn't a coherent answer to it, because it's not a question of objective fact at all, it's a question of values, and what one's personal preferences are. And those are inherently subjective. You value health over the pleasure of eating Twinkies, and so you tend to think of health as the "rational" choice. But someone else might value the pleasure of eating shitty junk food over health, and thus view eating Twinkies as the rational choice, and view the pursuit of that pleasure as being in their own self-interest - which, of course, it is.
Personal preferences. Values choices. This is the language of subjective judgement, Dom, and no matter how hard you try, you can't glue that to a basis in objective fact - people's personal values and preferences just don't work that way. Whatever I happen to value, whatever my interests are, pursuing that is my self-interest, and trying to argue otherwise is just you substituting your choices for mine, and arguing that your subjective preferences are "objectively" better than mine.