There are at least three objections to the risk of an unfriendly AI. One is that uFAI will be stupid - it is not possible to build a machine that is much smarter than humanity. Another is that AI would be powerful but uFAI is unlikely - the chances of someone building something that turn out malign, either deliberately or accidentally, is small. Another one that I haven't seen articulated, is the AI could be malign and potentially powerful, but effectively impotent due to its situation.
To use a chess analogy: I'm virtually certain that Deep Blue will beat me at a game of chess. I'm also pretty sure that a better chess program with vastly more computer power would beat Deep Blue. But, I'm also (almost) certain that I would beat them both at a rook and king vs king endgame.
If we try to separate out the axes of intelligence and starting position, where does your intuition tell you the danger area is ? To illustrate, what is the probability that humanity is screwed in each of the following ?
1) A lone human paperclip cultist resolves to convert the universe (but doesn't use AI).
2) One quarter of the world has converted to paperclip cultism and war ensues. No-one has AI.
3) A lone paperclip cultist sets the goal of a seed AI and uploads it to a botnet.
4) As for 2) but the cultists have a superintelligent AI to advise them.