But the larger reason is the more important. We live in a culture where very large amounts of money are made by making people fearful. Our economy is driven by advertisers and media who want your attention, and the two sure-fire ways to get your attention are to titillate you or to scare you. It can't be avoided. Franklin Roosevelt had the same fear in 1933, and we should listen to him.
Fear can debilitate, and fear, most of all, can make people irrational.
Think of the Johnny Carson toilet-paper shortage. Within 48 hours there was one. The supply of toilet paper was exactly what it should be. But people were afraid there might be a shortage, so they bought a few more rolls than they needed. Their friends saw them do that and did likewise.