Quick answer
More wicked people means more wrongdoing, which sounds obvious until you notice what the second line does with time.
Read both lines
The first line is arithmetic rather than insight: numbers rise, offenses rise. What the verse is actually for is the second line, and it is written to people living through the first.
The righteous will see their fall is a promise about witnessing rather than about acting. The righteous are not told to bring the fall about, and they are not told when, which this book consistently refuses to say. What they are told is that they will still be there. That is a smaller comfort than it first appears and a more durable one, and it is the same note chapter 28 ended on when it said the righteous increase after the wicked perish.
Related: Proverbs 28:28 · Proverbs 29:2 · Proverbs 24:19–20 · Psalm 37:34
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.