It is in these situations where the human performing the manipulation is the one responsible and not the victim.
Put another way, if you discovered that you were incidentally killing children each time you drove down a particular road, would you choose an alternative road or drive faster in an attempt to avoid detection?
There are all kinds of products we know people will misuse for violence (guns, cars, knives), but we do not hold makers of these products accountable because it isn't reasonable to blame them for what a fringe minority do.
Humans built ChatGPT. Should they remain accountable for what it says and does? If not, at what point do they get to offload responsibility?
Charles Manson, didn't commit any murders himself, is he innocent?
People undergoing psychotic delusions are definitionally not 100% culpable. If you say that people are 100% culpable despite mental state outside their control, I'd like to have you sign some things after you drink this scopolamine.
> it being the fault of a chat bot
It's contributory negligence. The chat bot could be designed to recognize psychotic delusions and urge the individual to seek help. Instead, it is negligently allows to reinforce those delusions.