To see the horrendous things happening in the world today your first instinct may be to think that mankind is doomed. There is one main thing to prevent us from completely annihilating ourselves, however, and that is the force of good. There are walking Angels on this planet all around us; people who remain optimistic and kind in the face of evil.
Stephen Hawking has a point, but it appears to be a bit heavy on the fact that the idea of wiping out all of mankind is a strong statement. It is amazing how quickly severe issues become resolved when it comes to situations where there is an event happening that needs the attention of many. Wiping out mankind is one way of saying that we need to focus on the more severe issues that are facing our world today. In the long run, I think the lack of passion for one another may destroy much of what we believe, but hoping a balance of love and anger will fuel the need for answers.
For example, right now people have nuclear bombs just waiting to be used(For example North Korea) and could wipe us all out. Albert Einstein said "I know not what weapons World War IV will be fought, but world war VI will be fought with sticks and stones." What he means is that World War IV will be the death of us all and what I think is that it will be a nuclear war. So maybe he is a little pessimistic, but it's the truth and that can't be called pessimistic.
Stephen Hawking was not being too pessimistic with his point of view. Human civilization is pretty barbaric outside of electricity, and we aren't exactly doing our part to preserve our own habitat. If we don't wipe ourselves out, the only other option is eventually fading into history as we evolve, so self destruction is not really all that bad.
Yes, I think Stephen Hawking is being too pessimistic when he says that mankind will wipe itself out. I am sure that he and I would have a very intelligent debate over who is in charge of the direction of mankind. I am firmly grounded in my beliefs as a Christian, therefore, I know that only God has the power to take us the direction he wants us.