Why is it unwise to use violence to get what you want in life? It is because although you may gain in the short term, you will lose bit time in the end. Too many people live for the short term good - even if it results in harm over time. This is why the godly father takes time to warn his son against using violence to get what he wants in life.
This dad uses a great picture to explain to his son why violence is not a good alternative to get ahead in life. He speaks of how it is useless to set a net with bait right in front of the bird that you are wanting to catch. The bird sees not just the bait, but more importantly the net. As a result he will have nothing to do with the set up because he knows it is a trap. This is a lesson from hunting 101 - and one that even those who know nothing about hunting can understand. But then the father uses this very simple illustration to prove a very important point to his boys.
When someone uses violence to get what he wants, he is not lying in wait for the other person as much as he is lying in wait for his own life. Sure in the short term he may attack a few people, spill some blood getting what he wants, and get a little gain. But in the long term he is only setting a trap for himself. Worse that this he is setting his own trap right in front of his own face - and not realizing it. He is setting a trap for his own demise and destruction. It sounds pretty silly that someone can set a trap for themselves and ambush their own lives - but that is exactly what this young man is doing.
The father then ties this lesson up for his son by telling him that this is what is happening when someone wants to gain by violence. It may get him something immediately, but it will take away his life when it is all over. This father is teaching his son something that is absolutely essential to living a life of wisdom. It is the lesson that the quick way to something is most often the unwise way to it. This is especially true when this quick way causes us to disregard Scripture - and walk in a way that is contrary to godliness.