If we look at the Spanish flu, the economy recovered pretty well after that, although the war also ended which may have had something to do with it. Look at it this way: even if 20% of people are really sick and can't work, that's still 80% of people working, which is way more than the near 0% of people working if there's a complete lockdown. And even in the worse case of 2% of the population dying (and all being working age; in practice we'd expect most to be retirees), that would on average reduce GDP by 2%, which is way less than it's predicted to fall if there's a 2+ month long complete shutdown.
What about if people panic and stop shopping / going to bars, restaurants etc? Well clearly there's still a non-insignificant proportion of people interested in patronising those businesses even with the virus around, otherwise lockdown measures wouldn't be necessary because everyone would be staying at home anyway.
20% are sick and can't work. Then a good chunk of other 80% are not needed because a good chunk of customers are gone. Then quite a bit of people are scared of getting virus, ain't in the mood because of their relatives dying and/or economic situation and don't consume. Demand goes even lower. More people loose their jobs and demand goes even lower. And the spiral continues.
Bars and restaurants are great for spreading the virus. Once people learn it the hard way, remaining people won't go there that much.
In my country patronising of bars and restaurants fell down the cliff in a couple days mid-march. Closing them down due to quarantine was just a formality in many cases. Sure, some people would still go. But they wouldn't have enough traffic to cover fixed costs.
If we look at the Spanish flu, the economy recovered pretty well after that, although the war also ended which may have had something to do with it. Look at it this way: even if 20% of people are really sick and can't work, that's still 80% of people working, which is way more than the near 0% of people working if there's a complete lockdown. And even in the worse case of 2% of the population dying (and all being working age; in practice we'd expect most to be retirees), that would on average reduce GDP by 2%, which is way less than it's predicted to fall if there's a 2+ month long complete shutdown.
What about if people panic and stop shopping / going to bars, restaurants etc? Well clearly there's still a non-insignificant proportion of people interested in patronising those businesses even with the virus around, otherwise lockdown measures wouldn't be necessary because everyone would be staying at home anyway.