> because evolution made us naturally opportunistic as part of our survival mechanism.

I don't necessarily believe that and even if that is true our entire existence as humans is about overcoming god, we fight it every day.

>Give a human any system and they will attempt to exploit it. The real benefit of capitalism is the check and balance. I don't let you cheat because it costs me money and you won't let me cheat because it costs you money.

This just isn't true, companies are becoming more and more consolidated every single year, hurting competition, consumers and especially the workers. It is in the name, capitalism benefits capital owners and people who make money off of other people's labor, not the workers. So unless you're going to show me the keys to your factory, I don't see why you're licking the boot.

>Can you give any example of non-capitalism governments that don't have greed and sustainability problems?

What does this even matter man? Let's assume your premise is true, so what people are corrupt? Does that means the richest country on earth can't provide people with housing, education, healthcare and ensure that workers see more of their surplus labor value?