History is filled with blunders and mistakes so epic that they literally changed the course of humanity. What do you think was the biggest mistake in human history? If you’re Princip, this is nothing short of serendipity.”5. So not really a “mistake” because it brought OT, minimum wage, and other things, the 5-day work week is a mistake that has grown into an unstoppable monster.”11. What do you think was the biggest mistake in human history?