I'd be interested in seeing data over a long span of time, with some kind of metric used to objectively measure the level of greed in people or world leader, but I don't think you could product that kind of evidence. I'm not sure your claim is justified for now. One thing we can demonstrably show is that media coverage of negative events had drastically gone up over time. We are now readily informed about every horrible thing occurring in every part of the world, as it happens.
We now have more leaders who are elected by their population than ever before. I'd like to think that creates some accountability, and while it might not be as much as we'd like, it's certainly more than a hereditary monarch or warlord of the past.
Honestly, I think the problem is interest groups worried about their finances, who intentionally create propaganda to confuse poorly educated people and obfuscate the issues. We saw this with smoking, where cigarette companies paid doctors to claim that cigarettes were safe leading to a "controversy" among experts that played out for decades longer than it should have. We see this will fossil fuels now, and climate change, and evolution, and social justice. The internet has really become a double-edged sword, and we're awash in biased narratives that have been purposefully created to confuse us. It takes some good critical thinking skills to navigate, and half of the US has been indoctrinated to avoid critical thinking and believe claims based only on feelings or cultural traditions. I don't know the solution.