The prince that wanteth understanding is also a great oppressor; literally, and rich in oppression. Ewald, Delitzsch, Nowack, and others take the verse, not as a statement, but as a warning addressed to the ruler, as we have so many addressed to a son, and as the author of the Book of Wisdom calls upon the judges of the earth to listen to his admonitions.
They therefore render thus: "O prince, void of understanding, but rich in oppression!" The wording and accentuation of the passage confirm this view. Caher renders, "A prince that wants understanding increases his exactions."
The want of intelligence makes a prince cruel and tyrannical and callous to suffering: not possessing the wisdom and prudence necessary for right government, he defrauds his subjects, treats them unjustly, and causes great misery.
See the prophet's denunciation of Shallum and Jehoiakim for these very crimes (Jeremiah 22:13-19). Septuagint, "A king wanting revenues is a great oppresser ( συκοφάντης)." He that hateth covetousness shall prolong his days (Proverbs 15:27).
The prince addressed is thus warned that his oppressive acts will be visited upon him judicially; that only a ruler who deals with his subjects liberally and equitably can attain to old age, and that his conduct will shorten his life.
An early death is reckoned as a token of God's indignation. The second hemistich Caher translates, "But he who hates lucre shall reign long." Septuagint, "He who hateth iniquity shall live a long time."
(For "covetousness" (betsa), see on Proverbs 1:19.