Flu normally kills about one in a thousand people who are infected and about one in five catch it in an average year. So one in five thousand die. America normally loses 60 to 70 thousand people in a typical year. If the world was the same there would be around one and a half million deaths.
We don't know how many people would be infected by COVID-19 if we just let it take its normal course and we do not know how many will die. But a 2 percent death rate for the infected and half the world's population would be in the range of figures commonly cited. This is one in a hundred dead. For America that would be more than three million and for the world about 80 million.
But if we do not fight COVID-19 and fight it fairly hard the peak period of infection will overwhelm our medical system and might double the death rate. In that case we could see more than 6 million dead Americans in the space of a few weeks, and for the world about 160 million dead.
Note though compaired to the regular flu the death could easily be a hundred times greater. It will be as if we were hit with a century of flu in a few weeks.
But in one area it will be far worse than that. The flu takes old people, often just months before they would have died anyway and those last few months are generally far from pleasant. This is why the flu is called the old man's friend. I know my own father said the first 88 years were great but I could have done without the last one. This is not so true with COVID-19.
If we do not succeed in flattening the curve and the medical system is overwhelmed a lot of people who had years and even decades of pleasent life, and in some cases even productive life will die.
Of course, the flu does have one problem that thankfully COVID-19 does not. The flu does kill infants, the very young, which for the most part COVID-19 does not. My own father lost an infant sybling in the 1919 flu.
So now you know why the extreme measures are being taken for COVID-19 while we treat the flu as part of life.