In the show "Person of Interest", there is a "good" AI and a "bad" one that fight each other in the real world. The bad Ai sends text messages or emails to random people and works with reinforcement-techniques: "I just transferred 500 Dollars to your bank account. If you deliver this package to that address, you will get another 1000 Dollars".
And people mostly just follow these instructions, without questioning them - because they get paid.
So yes, even today, an AI gone wild/rogue would have the means to do a lot of damage in the real world, just by bribing, tricking or extorting real people.
We have yet to see any major, disruptive scientific, medical or technological breakthrough entirely created by Ai. However, we already are observing "disobedience" (for lack of a better term) and a real potential to do plenty of damage to mankind, even up to its extinction.