"It is not fitting for a fool to live in luxury, much less for a slave to rule over princes."
We have in this proverb two situations that just don't fit with how things should be. The first is a foolish person with great wealth who lives like a king. The second is a slave ruling over princes. Lets look at both these situation to see what is wrong in them.
The rich fool
This foolish person seems to have come upon sudden wealth. He doesn't have the wisdom to gain wealth on his own. So perhaps he won the lottery or received an inheritance. A foolish person can't manage his own bit of money. So if a fool receives a lot more money, you can bet he will waste it for he has never learned to wisely use his wealth. He will waste it on indulging his sinful pleasure, and in the end he will meet again with poverty. This scenario is played out many times when people win the lottery. Since they are incompetent with money, they will mismanage the money they won and ruin themselves.
The slave who is king
Generally slaves are not prepared to rule countries. They learn to take orders without hesitation, not give orders. They usually don't have to think through a plan or idea. They don't have to organize to get a project done. They are told what to do and how to do it. For a slave to rise suddenly to the rank of king would be a tragic calamity. The slave has never been trained or prepared to do that sort of work. For him to rule over men who have been trained for that position is wrong. It is likely that the slave will become a horrible despot as he is intoxicated with power. This situation is worse than the last because the rich fool will ruin himself only, but this slave king will ruin a whole country.
It is important that before a person find himself with wealth, power and responsibility that he be trained and prepared for it. For example, we need to teach our children how to wisely manage money when they are young. Having been equipped with that skill, they will do much better when they are older and handling larger sums of money. Too much responsibility early on will crush us. It is good to give more and more responsibility as a person shows himself faithful in his work. A mother of one child can't imagine how a mother of five can handle all her children. But you learn to carry that responsibility a little at a time, unless you have octuplets.
This principle is also how God works as well. He trains us and prepares us so that we will be able to manage greater roles and services for Him. He knows us and what we need to do the tasks he has called us to. This we can see in the selection for elders. Ideally an elder needs to be someone who is more mature in His walk with God. A new convert or immature Christian is unprepared for the challenging work of an elder. 1 Timothy 3:6
We also see God using the principle in this proverb in the 'Parable of the Talents' in Matthew 25:14-30. There we learn that the faithful use of the gifts and responsibilities that God has given to us in this life, will bring us greater responsibilities and rewards in the life to come. God is using this life for the believer as a training ground for the life to come. If we are faithful to use well all the gifts and opportunities God has given us, God will give us more in the new heaven and the new earth. This is the principle that we find in the proverb we are looking at today. So let us be faithful servants of God so that we may produce much fruit to the glory of God.