Who's "we" in this context? A lot of people around the world don't get to be part of that "we" and their problems are ignored. Which is probably why some of them amass assets in Switzerland.
You, and me. That's who. The world did it together. I don't know who you are talking about who didn't benefit?
People in developing countries where the major powers play at regime change. Countries whose problems are irrelevant to geopolitics. Countries that are simply robbed or attacked by major powers or their allies.
2. Nation states fight with each other. A global government that controls trade and the military would end that dynamic by making the nation state obsolete.
Not really. Armed conflicts arise over conflicts over how to share a resource. A world government won't fix that. Your assumption rests on the faulty assumption that wars are the result of angry people just hating each other. Nazi Germany didn't invade the USSR because Hitler hated communism. Germany wanted access to the Baku oil fields. All conflicts are like this.
A world government would need a monopoly on the legitimate use of force, and the police/military strength to enforce the law. The US states can't go to war (anymore) because the federal government is strong enough to crush any attempt.
I think rule of law is critical to making global government work. If nations could treat this hypothetical world government like countries treat the UN then it would be pointless.
The reason the US states aren't at war with one another is because USA is well run. If it wasn't, they would be. It's not a hard concept.
That's a pretty trivial point. I don't disagree but I don't see how it makes any difference.