"Indeed it is useless to spread the baited net in the sight of any bird"
Solomon is incredulous over the willingness of the fools to walk into a trap they know was set. The believer has three enemies: the world, the flesh, and the Devil. Each of these sets different traps in order to capture, incapacitate, damage, or destroy the person in their living for Jesus Christ. We know what the traps will be, and yet, each week people walk right into them and do great damage to themselves.
This is the Hebrew word hinnam, which means out of favor, useless, in vain. In this case Solomon is pointing out that if you show birds where the nets are, they will fly around them even if they have some lures in them. It doesn't do any good to set traps that the prey knows about, but this is not the same for the selfish person. They want what they want when they want it. They will walk right into a trap that will destroy their life, just to get the selfish pleasure they want. People in Solomon's day – and in our day – want money, sex, power, and fame; and they will walk right into a trap to get it. Even though they see what happens to people who gain these things, they still go after them somehow ignoring the consequences or thinking that this won't happen to them.
We know that being famous creates a prison in which you can't go out in public and do not have the freedom of a normal person and yet people still seek this.
We know that sexual unfaithfulness allows all kinds of diseases, emotional pain, guilt, and even unwanted pregnancies and yet people still dive right in pursuing it.
We know that drug use shortens your life span, destroys relationships, leads to criminal behaviors, destroys potential, damages your body and brain, and yet people still do it even though they know it is a trap.
We know that absolute power corrupts absolutely and causes people to compromise their values, lie, wound, participate in many unethical practices, and yet people claw and scratch and fight to have more power.
This is the Hebrew word kanaph, which means wing. Clearly Solomon has in mind a bird, and he uses the bird to be a symbol of the freedom that it has and the intelligence it has to not get caught. It doesn't want to get caught, so it avoids places with nets.
in the sight of
This is the Hebrew word ayin, which means eye, before, before the eyes, sight. The idea is that the bird is not so stupid to go into a trap that it knows is there.
Solomon gives us a picture of how gullible our selfish desires make us. He is pleading with us to be wise. Don't be lead around by the nose like some trained circus animal just waiting for the next morsel doled out by your handler. Be wise – don’t get sucked into the traps of selfishness. Sure, selfish pleasure is enjoyable; but it will put you in a slave labor camp eventually working for your selfish pleasure instead of the other way around.
Realize that God wants you to enjoy life and will crown your life with the very things that you could selfishly pursue near the beginning of life, but He will do it in a way that does not wound you or anyone else. He will give you honor, wealth, and intimate relationships within the boundaries of righteousness if you would just learn wisdom.