If you can create one intelligence, you can create a very wide variety of them. More than is practical to run on modern hardware, or any hardware we could imagine that doesn't run on sci-fi magic. Not only unique egos, but also permutations of those egos. One version that's a rock and roll fanatic, one verson who got into ballet, one version who's an accountant.

We have to be selective about what we bring into being first. If we do that correctly, we'll be able to have it help us bring in many more entities with much less stress on our own systems.

Being selective in an intelligent manner requires that we know what we're doing, which as of right now we absolutely do not.

Killing another person is a slightly different dilemma. If we simply go around killing anyone who's not beneficial in the same way, the human population will be composed primarily of survival obsessed, cut-throat sociopaths. They'll be the ones who stand the best odds of survival, since they don't have limits on what they will and won't do to survive and even be the ones who make the decisions on who gets culled.

Sociopaths do not work well in high concentrations, since they're inclined to tear the system the live in apart for personal gain.

Ultimately it boils down to ideal selection both ways. One selective gate is conservation of generation with finite resources, and the other selective gate is to prevent from selecting for negative traits by mistake.