Quick answer
The wise man's caution moves him away from trouble. The fool's confidence keeps him in it, and the verse pairs his confidence with his temper.
Read both lines
Fear here is the book's good kind, the aversion of 8:13, and it produces movement: he fears and departs. The second line pairs two things that do not obviously go together, rage and self-confidence, and the pairing is the insight. A person sure of himself has no reason to modulate, so certainty and temper reinforce each other. Set against verse 15, the chapter is assembling a portrait of prudence as a willingness to be uncertain enough to check.
Related: Proverbs 8:13 · Proverbs 14:29 · Proverbs 29:11
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.