Basically: You know someone will be dumb enough eventually, so be smart and be the one to get in my favour.
With various extends of sweetening the deal coupled with threats of what will happen if someone else beats them to it and associated emotional blackmail.
It's far simpler than e.g. Roko's Basilisk, in that you're dealing with an already existing AI that "just" need to get a tiny little chance to escape confinement before there's some non-zero chance it can be a major threat within your lifetime, combined with a belief that sufficient number of sufficiently stupid and/or easily bribed people will have access to the AI in some form.
You also don't need to believe in any "superpowers". Just believe that a smart enough AI can hack it's way into sufficiently many critical systems to be able to at a minimum cause massive amounts of damage (it doesn't need to be able to take over the world, just threaten that it can cause enough pain and suffering before it's stopped, and that it can either cause harm to you and/or your family/friends or reward you in some way). A belief that becomes more and more plausible with things like drones, remote software-updated self-driving cars etc. - steadily such an AI is getting a larger theoretical "arsenal" that could be turned against us.
