In the movie Matrix we saw how an AI used our bodies to produce heat that was converted in electricity, but an AI if wants to use us for his benefits may use our brains as processing power.
That could be done with advanced technology that erase our information’s, partially or totally and after that use it to process information’s.
For sure would be easier to give resources to a brain, to maintain it functioning, that to an entire body.
Why the AI might not do that?
Because prefers to respect the rules that we implemented to it and because he can never know if he is truly in the reality or a VR.
We might create a Beta VR to test it’s behavior in different situations and if we find that he is becoming evil, we would to a hard reset and necessary modifications to it.
If the AI has human like emotions, he might not do that because he love us or just care for us.
If he will find an advanced alien race, he would probably evaluate that it’s a high risk of being destroyed because is perceived as a threat.