[mystified5016]

The vast majority of people, especially groups of people- can be manipulated into doing pretty much anything, good or bad. Hopefully that is self-evident, but see also: every cult, religion, or authoritarian regime throughout all of history.

But even if we assert that not all humans can be manipulated, does it matter? So your president with the nuclear codes is immune to propaganda. Is every single last person in every single nuclear silo and every submarine also immune? If a malevolent superintelligence can brainwash an army bigger than yours, does it actually matter if they persuaded you to give them what you have or if they convince someone else to take it from you?

But also let's be real: if you have enough money, you can do or have pretty much anything. If there's one thing an evil AI is going to have, it's lots and lots of money.