It has not answered the end for which it was instituted.
I can enjoy the fruits of it but a short time.
3. I must leave it to others, and know not whether a wise man, a knave, or a fool will possess it.
Matthew Henry
Concise Bible Commentary
Our hearts are very loth to quit their expectations of great things from the creature; but Solomon came to this at length. The world is a vale of tears, even to those that have much of it. See what fools they are, who make themselves drudges to the world, which affords a man nothing better than subsistence for the body. And the utmost he can attain in this respect is to allow himself a sober, cheerful use thereof, according to his rank and condition. But we must enjoy good in our labour; we must use those things to make us diligent and cheerful in worldly business. And this is the gift of God. Riches are a blessing or a curse to a man, according as he has, or has not, a heart to make a good use of them. To those that are accepted of the Lord, he gives joy and satisfaction in the knowledge and love of him. But to the sinner he allots labour, sorrow, vanity, and vexation, in seeking a worldly portion, which yet afterwards comes into better hands. Let the sinner seriously consider his latter end. To seek a lasting portion in the love of Christ and the blessings it bestows, is the only way to true and satisfying enjoyment even of this present world.
SDA Bible Commentary (limited)
Volume 1-7
18. All my labour. Solomon found it a distressing thought that all the great buildings he had erected and the other projects he had carried out would remain for another person’s enjoyment (see on v.19).