Maybe it uploaded all the minds it was programmed to help, and then ran them all on a series of small, incredibly efficient computers, only sending duplicates across space for the security of redundancy.

A few hundred parallel copies around as many stars would be pretty darn safe, and they wouldn't have any noticeable effect on the environment. We could have one around our sun right now without noticing.

And maybe the potential for outside destruction is better met by stealth than by salient power.

If it doesn't favor just making more people to have around, why should it ever go on beyond that?