In The Prodigal Son parable, the setting represents the kingdom of God. Naturally, God's kingdom would be a rich setting. In Psalm 50: 10-11, the Bible states that God owns it all:
10For every beast of the forest is mine, and the cattle upon a thousand hills.
11I know all the fowls of the mountains: and the wild beasts of the field are mine.
The Prodigal Son represents wayward children, those who have strayed away from God and his kingdom.
In Luke Chapter 15, Jesus was sharing parables about those who had strayed from God's kingdom. Then Jesus shares another parable along the same lines. The parable is about the Prodigal Son who left his father's home.
No doubt, the setting of the father's rich homeland is a representation of the kingdom of God.
Remember, the Prodigal Son is still his father's son. Although he had it all, he wanted another setting--the world. He wanted freedom to see the world and all that it had to offer.
After wasting all that his father had given him, the Prodigal Son realizes that the world has nothing to offer but heartache and disappoinment. The Prodigal Son returns home to a setting which has everything he needs.
The two settings are compared--the father's house and the world.
No doubt, he will wander no more. He will most likely be grateful for all that he has in his father's setting.
Truly, the setting in The Prodigal Son parable is a representation of God who is our father and his kingdom which is our eternal home.
There are two aspects of the setting for this parable that are important for the lessons taught.
First, take the context in which Jesus actually brought up this parable. He was eating with tax collectors and the Pharisees criticized this behavior as a sign of social acceptance of those who were "sinners." In the parable, there is a direct parallel between the prodigal son and these tax collectors, the father in the story and Jesus (or God the Father), and the older brother in the story and the Pharisees.
Second, in the parable, the father is rich because he is supposed to represent God the Father, who, according to the New Testament, has an inheritance in Heaven for all of his "children." This youngest son of the father took his inheritance early and squandered it. This could represent humans taking spiritual or even material gifts (like money) and wasting them in ignorance. The wasting of the gifts also represents a turning away from or rejection of the father and his love. When the son comes home, finally, to confess with shame and embarrassment what he has done, we expect the father to respond with disappointment at the very least, and anger or hatred at the most. We see neither. The father is not only overjoyed, but displays his joy outwardly by bestowing upon this son even more material gifts (a ring on his finger, a feast of the fatted calf).
The point is to show that God the Father, who is "rich" in an un-Earthly way, celebrates lavishly when one of his children repents and returns to him. Like the parables of the Lost Coin and the Lost Sheep, the point is to show that every single soul is important to God, and a repentant heart is worth all the riches in the world.