Adam Clarke on Deuteronomy 24:18

Thou shalt remember that thou wast a bondman - Most people who have affluence rose from comparative penury, for those who are born to estates frequently squander them away; such therefore should remember what their feelings, their fears, and anxieties were, when they were poor and abject. A want of attention to this most wholesome precept is the reason why pride and arrogance are the general characteristics of those who have risen in the world from poverty to affluence; and it is the conduct of those men which gave rise to the rugged proverb, "Set a beggar on horseback, and he will ride to the devil."