You’ve completely misunderstood what I mean when I say “human nature isn’t going to change”. I’m not saying that all humans are greedy, or going to abuse the system. The “human nature” I’m talking about is the variability of peoples’ personalities. This guarantees that at some point, no matter how idyllic the society you’ve created is, someone is going to come along to break it. And they may not even be acting out of malice. It might simply be that they think they can do it even better. Any system you set up needs to have mechanisms to deal with that.