With the ancients, dates the age of the elders to whom rulership was given by God. Princes, designates underling rulers, or rulers of lower rank within the hierarchy of a government or any organization.
God promotes and God demotes. It is God who places the custody of His people, into the care of rulers throughout history.
It is unfortunately those rulers that fail in their responsibilities, and abuse and take advantage of those over whom they rule, for their own personal advantage.
All people on this earth belong to God. All people on this earth are given by God, to rulers for the sole purpose of providing a safe and productive environment such that each person can advance in Gods plan.
Unfortunately both rulers and ruled fail and thus trouble ensues. Both get greedy, while the rulers lust for more, and the ruled lust for something for nothing. Both are irresponsible and guilty of infractions.
However, here the rulers are in view. And whether you are a parent with children under your rule, or a president of a country, or anything in between, you were placed there at Gods discretion, and given authority under Gods rules, not yours.
Throughout history rulers in all categories have failed due to sin. All manner of sin.
The vineyard is the productive vine of the garden, the nation of Israel, the family of believers of God, the children of humanity. Sin has taken away that production. People have destroyed their own benefits.
The spoil of the poor, is a reference to that which legitimately belongs to others has been taken with illegitimate means.
This world, this universe, was designed and dedicated to those who belong to God. More specifically they belong to those who have been obedient to God in that they have advanced to spiritual maturity.
However, sin comes along and people reject God, reject Christ and thus try to take that which does not belong to them.
Spoils are the possessions that are taken at the point of violence or criminal activity.
Unbelievers are the quintessence of thieves. Believers who reject doctrine and their own spiritual growth, expect and take for themselves, that which belongs to the spiritually mature.
However, only the things of this world can be taken now, the things of eternity cannot be taken. So those who illegitimately take, take only that which is temporary and soon to be forgotten. They take the worthless and lose their inheritance.