Well …
journalists are responsible for most of that. (See:
https://xkcd.com/882/.) Most of the public health officials and the professional epidemiologists give a range of estimates based on the models (most more sophisticated then the simple equation I gave) and the available data. Hence the wide range of predictions; it's a brand new disease. Right now, Birx and Fauci are predicting between 100K and 250K deaths, but that was predicated on keeping the brakes on until mid-June. They are actually using a
low end prediction based on confirmed cases (and both of them kn0w that underestimates deaths) and one that assumes that we be able to get the virus under control with a vaccine. Romer doesn't think its wise to assume that and uses the base equation for a rough estimate of a pandemic that lasts at least 18 months and, perhaps, as long as 24.
What Romer is saying is roughly the same as what climate scientists have been saying for a long time: if we don't start doing something now to get control of the virus, our ability to effect its course may be minimal. And we'll pay the cost, both economically and in terms of lives. Personally, I don't expect us to take the action needed to control the virus and, barring a vaccine, I expect ~ 700K to 850K deaths by the time it s run its course. And that's an estimate based on a lower infection rate; Romer may be closer.
I'll save the post, however, and bring it up in a year so we can see who's right. I sincerely hope you are.