I will worry about hyperpersuasive AI when someone manages to come up with one that can talk flat earthers out of it...
The real Turing Test.
For an evil example, I imagine it would be easy to convince animals to eat poisoned food.
I do take your point though, the world is replete with causes which more or less look like averagely smart or even smarter people talked into campaigning for something that is against evidence, sense, morality or reason - or all of the above - which are also probably (or provably) against their own interests. I'm sure everyone reading can provide their own examples but please don't. I remain unconvinced that this sort of persuasion scales neatly with intelligence, though.