Despite all this, what are currently the things you experience, participate in or know of that keeps you feeling optimistic ?
Instability isn't always bad. It's how we put aside feudalism.
Climate change could make the Northwest Passage viable and open up a lot of valuable land.
Inequality has been going down. This is generally true around the world, and has been for decades. More recently, it is true within the USA: http://archive.is/lRxSi
I specifically said "More recently" regarding the USA, so why object to it being over two years? Two years is recent. Things have gotten dramatically better for the less-well-off people over the past two years. This is something to be optimistic about.
There's your problem. It is a choice---to be a sucker for the fear endlessly pumped out by most of the news media, or to be tuned into better things.
"You don't hire people and motivate them, you hire motivated people" -- Peter Drucker
"You choose to be happy" -- a bunch of old people
The first quote applies to extrinsic and intrinsic motivation. And I think it also can relate to optimism and pessimism. If you are looking for extrinsic sources to make you optimistic, then it will be fleeting. Find the optimism and the belief that the future can be better than the now in yourself.
The second quote, I don't recall where I read it. But the tl;dr was that someone went around and asked a bunch of old folks the secret to being happy. The majority response? You choose it. It explains why you can find happy people in poverty or miserable people bathed in riches. I think the same applies to feeling optimistic: it is a choice.
Knowing that I can be happier than I am now (even though I consider myself doing pretty good in that department) gives me reason to be optimistic and to strive for that. There are things I want to see and experience. There is more to life than I have yet to experience. I also know that my world could come crashing down; but I've been low before, and I can do it again, and again, seek being better than I might find myself.
All the things that news that you find yourself surrounded by: One, know that it is _designed_ to rope you in and invoke a negative reaction. Two, can you do something about it? If so, and it is meaningful to you, then do your part to improve it. If not, then don't. No need to have the world pull you down. Besides, there is always political/economic instability, polarization, and extremism. Climate change might doom us all; it might not. World poverty is diminishing and standards of living are leaping higher every generation. I think Stephen Fry did a neat little video a while back (can't find it) that showed the different countries of the world and their economic condition over the last couple hundred years: it all got better.
There will always be negative things. Sadness, loss, disparity, suffering, and outright evil. People have endured it, survived, and continue to lead happy lives. I think that is amazing, and helps me be optimistic.