There is no limit to all the people who were before them. Yet the successor will not be celebrated by those who come even later. This too is futile and a pursuit of the wind.
Solomon was himself a king, and therefore may be allowed to speak more freely than another concerning the vanity of kingly state and dignity, which he shows here to be an uncertain thing; he had before said so (Pro 27:24, The crown doth not endure to every generation), and his son found it so. Nothing is more slippery than the highest post of honour without wisdom and the people's love.
Commenting on Ecclesiastes 4:13-16
There is no end of all the people, even of all that have been before them,.... Before the present generation, the living that walked under the sun; a vast number they were that lived before them, and they were of the same restless temper and disposition; changeable in their affection and behaviour towards their governors; no end of their number, nor any stable affection for...
Notwithstanding their now worshipping the rising sun, the heir-apparent, I reflected that "there were no bounds, no stability (Sa2 15:6; Sa2 20:1), no check on the love of innovation, of all that have been before them," that is, the past generation; so also they that come after--that is, the next generation, shall not rejoice in him--namely, Rehoboam.