People will make bad choices at scale

“If you allow shops that sell otherwise banned products, some poor, honest, poorly educated mother of five kids is going to buy something that kills her. This is a prediction about a factual consequence, and as a factual question it appears rather straightforward—a sane person should readily confess this to be true regardless of which stance they take on the policy issue. You may also think that making things illegal just makes them more expensive, that regulators will abuse their power, or that her individual freedom trumps your desire to meddle with her life. But, as a matter of simple fact, she’s still going to die.” (Eliezer Yudkowsky, Rationality)

An illustrative example of People will make bad choices at scale and The Bad Button