Please identify the author and source of that quotation so it can be read in context.

I don't think there's anything in life, ultimately, that is not an attempt to serve self interest.

It seems to me that positions like "in the real world it's: "might makes right," "nature is red in tooth in claw," "everyone is an atomized, self-interested utility maximizer," or a New Age, "the world is love" etc. are more interpretive lenses than statements of empirical fact. They are ways of fitting empirical observations into a narrative. There are always plenty of counter examples, but these can always be read into the interpretive lens.

There might be various justifications for such an interpretive lens, but they cannot come from an appeal to a "real" world as filtered through that same lens, or else the justification is circular. It's sort of like how everything from anonymous self-sacrifice for strangers to extreme self-harm can still be rolled into "self-interested utility maximization," but only at the risk of making such a statement a vacuous tautology.

I think this is simply a pathological way of viewing the world, one hostile to human flourishing. Surely, it is better to be in a good marriage, based on love, than to be in a zero sum struggle for utility. That some people are able to paint everything in terms of "self-interest" is arguably just a sign of a sort of spiritual illness. This is precisely Dostoevsky's point in Crime and Punishment vis-á-vis the new social theories of his day.

At any rate, Homo oecononimicus wasn't born from "empirical findings" but exists in liberal political-economy from its earliest days, were it was simply borrowed from Calvinism. It's an unfalsifiable grounding dogma used to make sense of observations. The irony then is that society seems to make many positive efforts to transform citizens into Homo oecononimicus.