The crown of the wise is their riches: but the foolishness of fools is folly.
The crown of the wise (is) their riches; (but) the foolishness of fools (is) folly. Not riches, but "wisdom, gives a crown of glory" (Proverbs 4:9). "The prudent are crowned with knowledge," not with riches (Proverbs 14:18). Therefore the sense is, Wisdom (the opposite of 'folly'), being "the crown of the wise," constitutes their true 'riches,' and results in the heavenly riches; "but the foolishness of fools" is not "riches" to them, as 'the wise man's crown' of wisdom is to him, but is and continues "folly" - i:e., emptiness-neither an ornamental 'crown' nor enriching wisdom.