And there are a lot of lonely people out there...
Also, don't cults have a massive surplus of people-time as is? I get the feeling that, if I wanted to go and join a cult, it's not like they would tell me they were short-staffed and there was a waiting list.
More likely (and mundane) outcome is that people use it to create cheap online therapy services. Good ROI, clearly defined goals, very large addressable market, easier to find people willing to work on it.
My guess is that it'll be like "Nigerian prince" scams: it's not all that convincing. But even if it only works on 0.1% of its targets, that's still a large absolute number of people.
- Local presence of the cult
- Ability to operationalize victims (convince them to do terrorism, in your model)
- Ability of victims to "function" in society (hold down a job, do cult administrative stuff, earn money)
For an idea of what is the upper bound, look at Scientology or Jehovah's Witnesses. They don't have to use an AI to talk to people, they just hand out fliers on the street and talk to whoever is interested. Lonely people already today can sign up for Scientology, so the AI adds nothing.