'Foolish' in the Bible

And who knows [whether] he will be wise or foolish? Yet he will exercise control of all [the fruit of] my toil with which I toiled wisely under the sun. This also [is] vanity!

A poor but wise youth [is] better than an old but foolish king who no longer knows {how to receive advice}.

He begins by saying what is foolish and ends by uttering what is wicked delusion.