Honestly? Nothing. But then I've done nothing to make it worse either. If I had never lived, it would have made not one jot of difference to how the world is. That's not a statement of depression or nihilism. Just how it is.
At world level? Nothing At national level? Nothing State level? I pay my bills At city level? Same thing At neighborhood level? We do trick-or-treat lol At household level? I provide everything - I'm the man, man.
Nothing really. My contributions to the greater good comes more from things I haven't, stopped, and won't do. I think what people don't do in the name of the greater good is in truth more important and causal than what some do, do.