The only positive experience I've had with a chatbot was functionally not a chatbot, but rather a form I needed to fill out, but which was done in a chat style, presumably to be more user friendly. It wasn't bad, per se, but a normal form would have been better, but it wouldn't surprise me if this style of form-filling does generate less tickets than the normal approach, since it doesn't dump 10 fields the user needs to fill in all at once, but rather staggers them and give you one at a time. Even if half the things you need to fill in are 'full name' and 'date of birth' and the like, many people have a very low tolerance for overload when it comes to these things, and I don't think there's a good solution to that.
It's a similar problem to how power users only get in touch with support when all other options have been exhausted, and then get annoyed when they have to go through the motions and try everything again, knowing it won't work, which it then doesn't, and only after half an hour of dicking about can support actually do what they need to do. The problem is that Average Joe almost certainly hasn't exhausted every option, and it's even fairly likely that they went to call as their first option over anything else. The only difference now is that a chatbot is now available as first line of defence that doesn't take up the time of an actual human, rather than that being the phone, which very often will need a human on the other end, at least at some point. The chatbot doesn't even need to be good to pay itself back, so long as it solves some problems that then prevent some support calls, since human time is expensive.
We need that XKCD shibboleth or something to fix that, but even that is open for abuse, so I don't think there's an actual solution to be had.