I think that ambition is always positive and can never be negative. It is always great to have goals in life that you want to accomplish, and having ambition can give you the right motivation to make sure that they get done. Ambition is the drive that is needed to become successful.
Ambition is great it gets things moving keeps people inspired the question is really about the application of ethics and understanding that ruthlessness is the ethical question? Perhaps people that justify their ruthless actions in order to succeed and call it ambition is the problem. Ethical Ambition is a great concept and has conquered the problems of the world since the dawn of time.
Power, consumes people. And from that power, things like isis, and 9/11 happen because the ambition for power, leadership, and greed overcomes a person. Think of the tragedy of macbeth. He wanted to be kind so badly. And ended up murdering the king, and his best friend alond with many others to get a crown,