Fact: if we do nothing and don't buy time to prepare, our healthcare system collapses, a lot of people die and there'll be a lot of unforeseen consequences. You can say, think and believe that that's not much of an issue, but you can't proof it.

Your argument: "the economy is important, we can't do without"

Yes it is, but the economy will rebound like it always does. It will not disappear. We need to flatten the curve, gain more insight in other consequences. We don't need to lockdown forever, but we can't immediately reopen either. Both would be stupid, we need to find a middle ground.