1) 80% of Americans would get the disease That sounds scary (big number!!). But I'm getting tired of the constant reporting of each and every infection. What is really relevant is infections of at-risk groups. Most infections, nothing happens!
2) 8-15% of all Americans over 70 would die. Newsflash: Old people tend to die more often than young people. What is the all-cause i.e. normal mortality rate of the elderly. One number I saw cited: all-cause mortality of 83/84 yo's in the US ~7 percent. Case mortality rate i.e. with infection in Korea among 80+ yo's: 7.4 percent. What am I missing here? Are the reported covid mortality rates all normalized by all-cause mortality and they report only real "excess" deaths or are they lumping everything together? This would be so mind-numbingly stupid, I really hope I'm wrong about this!
3) 0.9% of them would die. That's the unconditional number, all age cohorts aggregated. Split them up and the number is clearly skewed by the large number of the elderly (and see 2 above). Now factor in that testing outside Korea, Taiwan etc. is really bad and focused on symptomatic cases. Common estimate of how high are the true numbers of infected is around one order of magnitude. Let's assume the official stats are off by a factor of ten. Let's further assume that young people (say, below 65) are "more social" or mobile than elderly and thus likelier to get infected. That means a) the undercount is dominated by younger people and b) the mortality rates are off by more than ten. At what point are we getting to mortality rates of common influenza?
4) There are basically two ways to die from the virus: a) immune system overwhelmed by virus or b) immune system overreacts. Younger, healthy people ( < 65 yo) seem to die more from b. Now look into who are the victims in this cohort and it turns out mostly medical professionals. Due to lack of preparation and equipment, those medical professionals are exposed to disproportionately higher or even extreme quantities of the virus. This seems consistent with b. Also, it means that the mortality rates of younger, healthy people is skewed by counting medical- and non-medical people together.
In sum, I think this is a total overreaction and panic that causes huge economic damage (which has a big human cost, in terms of lives lost, as well make no mistake) for what may turn out to be basically nothing.
What am I missing?
[EDIT: I'd prefer we focus on the at-risk groups (elderly and pre-existing conditions like obesity, cardiovascular diseases, diabetes, etc) instead of just blanket-everybody. Isolate the at-risk groups until vaccine and/or medication are developed and let everyone else basically develop herd immunity until then. Increase testing. And basically use this as a call for more general health measures, not just virus panic. The immune system depends on sleep, nutrition, mental health/hormone balance, etc. With the panic and the economic crash induced by it, all these factors are becoming negative instead of positive factors for most people now.]