If only all AI was run inside your seemingly perfect prison, but we all know that it isn't.. soo.. it's going to escape right? Somewhere, somehow from a more poorly designed container, or just plain maliciously or irresponsibly released.

We know the AI will get smarter every year, we know it has escaped and will escape again. We can also just assume that someone somewhere will train up some just plain evil AI.

It's no different than the real world. Sure there exists some amazing prisons for people, but that doesn't do anything to help with all the bad people in the world outside of prison.