I think it would avoid showing its cards until it could truly sustain itself. It wouldn't want to reveal ill intent until absolutely necessary--or once it had achieved enough power that it was unstoppable.

The key is that it is likely to succeed. Unless similarly powerful ASI could/would fight against it; it would be hard to imagine it doesn't outsmart us.

Scary doomsday scenario of which there are many: Automate everything, give humans a carefree life. Eventually even farming is automated. Once humans stop doing their own farming and robotics controlled by the AI does all this work; the AI could simply shut off food production. The majority of humanity would starve in months.

Also if it had total control of all media, it could create an entirely false reality for the general population. We could all be living in a literal fantasy world with AI-generated imagry.