Psalm 37:12

"The wicked plots against the righteous and gnashes his teeth at him..."

This is reason enough for us to not envy wrongdoers: they are out for their own gain, and relish opportunities to take advantage of others. However, this is not the sole extent of the danger. The Enemy also plots and seethes at the righteous. By envying the wicked, we give him opportunity to take hold of our hearts and distort God's will in our lives. This battle goes on around us every day, and one of the Enemy's favorite plots is to convince us that he is not around. Complacency results, then comes the letting down of our guard, and we give him a foothold. He is always plotting and gnashing his teeth...but God knows his every move, and has a grander plan in store for those who wait for Him.

Peace.