"So are the ways of everyone who gains by violence; it takes away the life of its possessors"
This is a summation statement regarding this whole section. Solomon does not want his new students to miss the point of the first lesson.
This is the same word that is used for violence. In fact, in this instance Solomon uses the same word basa. The idea is to cut off or gaining almost always in a bad sense. The word means to cut off or cut away and so involves a level of gaining but also a level of violence.
This is the Hebrew word basa, which means to cut off, gain, covetous. The idea seems to come from cutting a piece of cloth free from the loom that it was woven on. It also is used of cutting away profits or goods from their rightful owner; i.e., covetousness. The King James Version puts the emphasis on being greedy or covetous. The NASB translators put the emphasis on the violence or ripping away of the goods. The Septuagint puts the emphasis on stealing or trying to complete oneself through lawlessness.
This is the Hebrew word nephesh, which means life, soul, creature. Its original meaning seems to be the idea to breathe. It is the word that God used when He breathed into Adam his breath of life and he became a living soul.
The clear idea is that you may gain the item that you are looking for or the relationship you want, but you get something else with it. You get a flesh-eating, soul-eating disease. When one gains in this way, it begins to eat away at the life of the one who wanted to add to their life through breaking something away from its rightful owners. Notice the parallelism in the summation statement. A person cuts away something they really want to add to their life, but it takes away their life to have someone else’s goods in their possession.