Perhaps a different way to look at things is that while people are causing no end of trouble for each other, the planet they live on, etc. they also have a knack for just continually figuring out how to do things better and differently. People don't get exponentials so they get caught by surprise by them even when they shouldn't.
People can be fatalistic when faced with big problems. But when faced with smaller problems, they just start solving them. And lots of big problems can be broken down into lots of small problems. A big problem may seem insurmountable. A small problem is just work that needs to be done. Lots of people working on lots of small problems, means a lot of those problems simply get solved and melt away.
I don't have all the answers when it comes to world peace, clean energy, hunger, child mortality, sea level rises, etc. These are really big challenges. But I'm an engineer and solve problems for a living. A can-do attitude goes a long way to just getting stuff done.
A wise lesson that I picked up in some communication training is to try to steer workplace discussions towards being constructive rather than being dismissive, argumentative, and negative. By simply talking about challenges rather than problems you can rephrase things such that people start thinking about how they can make things better rather than how hopelessly bad they are. They get excited instead of angry. Using a "yes and .." instead of a "yes, but .." is a very subtle way to say the same thing in a way that is constructive.
In a workplace, prolonging a bad thing serves no purpose so getting people to talk about how to improve a thing is more productive than having them provide endless reasons why a thing cannot, should not, or must not be done. Get people to think about how they can do it better rather than talking each other out of doing constructive things. I can't fix everyone around me but I can fix how I voice my own criticism. That little lesson has served me well over the years.
As a startup CTO I have to be constantly mindful about the epic amount of shit I cannot possibly deal with while still making sure things get better month to month. For any twenty problems, pick two to solve right now. Ignore the rest. I can't afford apathy or fatalism. Neither is constructive. But I can park one thing and focus on a feasible thing. Once I solve that, we can see about the other thing.
My attitude to all the big problems in this world is the same. Yes they are big but there is progress and plenty of opportunities for more progress. Don't tell me how royally screwed we all are, tell me how things could be better and I might be able to do my little part to get us there.