Pretty much no proponent of free markets has advocated lawlessness. From an economic perspective, the law has to be designed to prevent actors from inflicting external costs on others (say, by stealing instead of buying, or by destroying valuable stuff that belongs to other people), and legal penalties have to be large enough that breaking the law as a whole makes less money than obeying them. "Cheating" is just another word for behavior we've decided inflicts costs to society as a whole.