@le_inferno , I think you are describing human ego, more than human nature. And the human ego can be suppressed with empathy, logic, meditation, prayer, evolution, or drugs.
The chain of logic that leads to selfish behavior was accurately described by you, and many people do live by that, and its why we still use locks, police and armies. But that is only the present, and it’s not a reflection of our inherent way of being.
There is enough land, food, water, and medicine for every human on the planet. Once people figure out how to share these resources without petty clinging arguments to capitalism or socialism or whatever… then world peace will be relatively easy to attain. Once people realize that if they resist their inner predatory selfishness, they enter into a silent contract that encourages others to also resist predatory selfishness. The gain from this collective realization is far greater than any loss incurred through the resistance to dishonesty and stealing.
The intelligent people who exist now already behave, as if world peace is here, because it’s logical to do so. Eventually through time and evolution, (the 100th monkey) that logic will catch on to most everyone else.