Epicurus was in fact fairly subtle as he developed this. Many actions which might look at first like they would bring pleasure to the agent turn out in the end to bring considerable pain. Thus, it might look like I would benefit if I could take advantage of someone else, but this might very likely lead me to be fearful of revenge, etc. Bodily pleasures like drinking or eating when carried to excess could also bring pain and suffering. Thus, Epicurus developed a position which advocated a somewhat restrained life in which one would try to limit desires so as to avoid disappointment and pain.
Ethical egoism is teleological.
Eudaemonism Eudaemonism is a fancy word which comes from the Greek word which means well-being. Thus, a good oak tree is one that grows tall and straight with a strong root system, a solid trunk, and rich foliage. A good scissors is one which effectively cuts paper and the other things that a scissors should be able to cut. Thus, the capacity to experience pleasure and pain could not be the highest purpose or capacity for a human. Aristotle associated these highest purposes and capacities in human beings with rational capacity.