Optimism is part of belief.
If pessimists are realists, then optimists are hoping to change that reality. I don’t buy into the idea that pessimism is the real way to see the world. That is only true if you don’t believe the world can change. Pessimists never really lead anyone to a different reality because they are not by nature optimistic enough to believe that the world can change for the better. The world is not without its problems, but the world has in fact changed for the better. That change came from those foolish enough to see past the real world to a world that could be. It takes belief to see something before it becomes reality. Leaders have the ability to see it and show it to others.