Seems AI won't need robot armies to take over, they will just convince us to kill ourselves and we will comply.
However, I think the venn diagram of people who are capable of manipulating someone to kill themself and simultaneously willing to knowingly do so barely intersects (high functioning sociopaths). Even if the limited number of them worked 24/7, their impact would be minimal.
AI on the other hand has no morals, or can trivially be programmed to not have morals and can scale infinitely. An AI can fairly easily make a facially reasonable argument that mass suicide is a net positive for the planet.