a. no need to be rude and b.
The same reason sane people drive automobiles which kill 40,000 people in this country a year[0]: the alternative can be worse.
How many people do you figure are going to get rolled back into poverty at 15% world GDP loss?
[0]Less this year I suppose.
A whole lot, but they'll get back to parity (on average) in about 6 years, assuming a 2.5% GDP growth. How many dead people do you think will come back to life after six years, in comparison?
I don't want to be glib, but I genuinely don't think you've thought this through. I just can't see a moral argument for allowing a 10M+ death count at the kind of economic impact we're talking about right now.
Then try thinking through the impact of what could become the biggest economic disruption since the great depression or the great leap forward. Those went well for people. 80 trillion GDP, down to 68, back to 80 in 6 years is a 36 trillion dollar loss in the next six years alone. That's 3.6 million per victim and to be frank, most people aren't worth 3.6 million dollars.
Look, this is a reasonable thing to disagree about but you aren't engaging in good faith.
edit: math
The hope is that it will work everywhere like it seems to have in Hubei and Korea -- near-zero new case counts and a regime of continued care, a few extra regulations, and pervasive testing. And it might work. But if it doesn't, yeah: we should turtle, accept the economic catastrophe, and wait for a vaccine. Would anyone sane argue otherwise?