Quick answer
A man committed to defiance eventually meets someone who does not negotiate. The verse states an outcome without naming who sends the messenger.
Read both lines
"Seeks only rebellion" describes a settled orientation rather than an incident: this is what he is looking for. The second line's messenger is left deliberately unspecified, which is characteristic of how this book handles consequence, and the word covers a royal officer, an enemy, or simply whatever finally arrives. What the verse does not do is describe God dispatching an agent in anger. It observes that a life organized around defying authority tends to encounter authority that has stopped being patient.
Related: Proverbs 16:14 · Proverbs 29:1 · Proverbs 11:21
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.