some inspired and high level thoughts there...a few small points for discussion from other studies:
a) Ego does not simply refer to how strong
is one's personal will to survive...this could be
attributed to lower brain voltage and wiring, or in some cases to ignorant ruthlessness...as wekk as one's choices and experience.
b) "Ego" refers to the mechanics of self-identity. Persons should not be considered simple beasts only.
c) Psychological warfare may influence someone not to save money...serving the ends of the person making war. In this case, you must admit, the person with making war might not have a "better" ego than the other, even if he prevails.
We cannot scientifically say evolution "deliberately"
develops ego and emotions for any purpose.
The Theory structure of Evolution would say
that ego and various emotions have resulted from natural selection and random mutation, time and chance. They seem to help or hurt statistically, the chances of a gene pool
surviving through the generations. Some may be vestigial, like the appendix, or even counter-productive, like some persons' love for addictive drugs, which can be partly inherited.
Ego and emotions may also carry seeds of destruction for a gene pool. For example, chimpanzees have a much smaller range in our Age, now that a more rational creatur (man) is expanding into the chimp areas. Chimpanzees have a kind of ego and emotions, but with those, are sometimes killing one another in rages without creating any advantage that we can see.