Nobody approves of the one who takes their property. You should always have a pessimistic outlook for your own sake. Apply my example to real life. Nobody, unless they come from a background of ultimate good which has rendered them incapable of seeing the evil in society, in their right mind will leave their wallet, phone, and car keys on a park bench and leave it unattended. Assuming that the players in RotMG are typical human beings, you, like the man who is thinking about leaving his items unattended, will never be fully safe. Accordingly, like the man, you are expected to take safeguards to protect what you own; he will carry his items with him, you will either pause, nexus, or watch your screen. Failing to follow these safeguards is just gross negligence.
I know I didn’t really answer your question about why you should assume the worst of people to keep what’s yours. I thought it would be a clearer answer to just apply my example and explain it. Many people have tackled human nature, and what we have is a slew of books which are just opinions that don’t lead to any definitive answer (Locke and Hobbes, I’m talking about you!). It’s much easier to just assume that some people are bad (a fair assumption) and build your actions around that assumption.
