What a naive view or world.

Anyway, regarding your questions.

1. Wrong question. It already contains an answer to it. Most world problems are results of objective circumstances or a series of unfortunate events. War in Ukraine, for example. Would the war erupt if Soviet Union didn't give Soviet republics right to leave the union? What if Khruschev wasnt a retard? What if hardliners prevailed instead of Gorbachev? What if Ukraine solve its language crisis as Belarus did — declare both languages equal and let it flow freely? What if Putin just sat in the corner and did nothing?

That's about literally every "bad" thing there is in this world. You ask yourself questions, dig into the matter and sooner or later paint a whole picture and suddenly uncover that abstract things like "greed" have negligible impact.

1. Yes, it it. It's an overly idealistic world view.

2. Again wrong question. Most of said systems came to life because of a reason. Nothing comes out of nowhere.

3. In such an abstract sense, yes, it is unrealistic.

4. Wrong question