The fear of the wicked will come upon him,
And the desire of the righteous will be granted.
What does man fear? He fears losing what he values most. The thing he puts his time into, where he finds his identity. He fears losing his career, his possessions, his home, his family. And in the end, all these things will fail him. They will all come to ruin. His fear will most definitely come upon him.
The righteous man is the one that fears and loves God. His desire is for the Lord. God will never fail, our desire for Him will certainly be completely satisfied.