[Potential Spoiler for Dune]

Hello everyone. I've just recently finished Frank Herbert's Dune, and am somewhat confused by a moderate-highly important plot point: What the Bene Gesserit women wanted to do with Paul/The child that Paul-if-female would've had. I'm led to believe that they wanted to use him to predict the future, but also they were trying to produce a super-mentat. Which doesn't really make sense, since they'd be trying to control something that:

A. Is able to use the Voice

B. Is (Do to being a super-mentat) highly intelligent, likely more-so than them

C. A human being, which tends to not like being a slave.

Am I missing something? Or are the Bene Gesserit's just stupid?