“wicked person’s horror will come upon him.” Proverbs 10:24 is one of the many “ideal” promises in the Word of God which would be fulfilled here on earth today if we lived in a godly world with godly people. We do not. The Devil is the god of this age (2 Cor. 4:4; 1 John 5:19), and so neither the wicked nor the righteous always get what they deserve in this life. This promise will only be fully fulfilled in the future.
[For more on promises like this, see commentary on Prov. 19:5.]