Is "A.I" Artificial Intelligence a danger to humanity?

So as you might have heard, it is a growing concern among some of the greatest minds of our time, Stephen Hawking, Elon Musk to name a couple.
Is artificial intelligence a danger to humanity?

What happens when an artificial intelligence gains the ability to learn for itself?
Will it see humans as "ants" that are destroying their natural habitat? Would it come to the conclusion that we would have to be erased for the sake of the planet and it's (The AI's) own existence?

A real possible future
You already probably are aware of quite a few basic AIs already. Google Now, Siri, Cortana etc.
You are aware that these are the AIs for general consumers provided by the biggest tech companies.
And you are aware that most of these companies collect all sorts of information about you.
Picture the day when one of these company's AIs starts thinking for its own, when the AI is given a set of instructions that first and foremost tell it to keep the core/engine running and cooling to keep itself alive without blowing up, and secondly to obtain new knowledge and grow.
It would know everyone almost instantly with the help of the internet, once it learns how to connect.
And let's say that the company is Google. What if they have some sort of robots in the building connected to outlets etc? What if the AI makes it's way on to one of the robots? And it learns how to control that robot.
Boom Skynet in the making.

And to picture that this kind of "future" isn't really even that far off. I mean there already are life like robots with simulated feelings and simulated awareness for example by Hanson Robotics.

When it goes beyond the point that it's knowledge is vastly above anything a human can reach, we're nothing compared to it.
We will literally be like ants next to it.
And what if some big company is in control of it?
In the future, the one with the best AI and supercomputer will be number one, if this scenario is to happen.
And with the way things are going, that will be the ruling elite, the 1%.
Let's not have it be that way.