Tobacco companies. Humans can be enticed by short team pleasing at the expense of their long term destruction.
Maybe outlaw ice cream next? Or how about marijuana smoking? (Oops, already tried that.) How about loud music (long term hearing damage)? How about motorcycles?
If an AGI starts inventing new and wonderful ways in which we can destroy ourselves, and we are taken in by it, we will have to restrict that, it's non optional.
You can make the argument that, say, current hard drugs should be legal - but I don't think there's a way to defend the position that any possible future 'thing' should always be legal/permitted regardless of negative effect.
In fact, likely much more harm than those with evil intent.