"You shall not covet your neighbor's house. You shall not covet your neighbor's wife, or his manservant or maidservant, his ox or donkey, or anything that belongs to your neighbor." Exodus 20:1-17.
That is, just look at your own piece of the pie, not the other fellow’s. You will look at what you have, not what someone else has. You will not act upon a desire for something that belongs to someone else. What's your is yours, what's theirs is theirs. You will focus on your property, not their property. It is not about them and what they have; it is about you, your journey toward God, and what you have along the way.
Why would God require this?
Implementing this commandment yields a certain kind of social structure. Not following it creates another. And the social structure in which people grow up and live their lives affects how people are trained up for God.
What are the practical consequences of this?