We obviously don't shut everything down because of 1 in 1,000,000 risks. We don't shut everything down for 250 in 1M risks (the flu).
Here we have what's likely to be a 1,800 in 1M risk, based on the latest infection fatality rate numbers and the estimate of how many people would be infected before herd immunity. It's 7x worse than the flu. It's also not a risk that it's clear we'll be able to avoid. So here it gets hard to reason about what's right to do.
And, of course, we obviously can't act to protect people at a level that will result in worse outcomes, like starvation or famine or collapse of public order.