Does egoism require rejection of naturalism?

[Anonymous No.12716017]

It seems like if we accept naturalism we are necessarily brought to a reductionist 'bundle theory' view of the self, wherein the self is a bundle of properties, a category, with no underlying substance (spirit) of which said properties are a part. In other words, there is no core substance, no spirit, which "takes on" our properties, and which would remain intact even if our properties were wholly replaced; instead, we are a collection of those said properties given the illusion of a cohesive self by our memories.
This means that we are not the same person over the course of our lives; we are only what we are at the present. Therefore, 'acting in self-interest' = acting in the interests of your present self, as serving the cause of your 'future self' would be the same as serving a foreign cause.

So, does egoism require the existence of the spirit?