1. Spend money to temporarily increase hospital beds and ventilator capacity, but keep everything else running normally, or;
2. Shutdown everything to slow the spread so that we don't need to increase bed and ventilator capacity.
I'm tempted to say that adding bed and ventilator capacity is cheaper. I don't think that option costs trillions of dollars, like option 2 does.
We can't create enough bed space, vents, ECMOs, in the next 6 months. We can't train enough doctors, nurses, etc in 6 months. So we play the hand we're dealt, and choose a mitigation strategy that doesn't result in 70M worldwide fatalities (6M in the US).
I think that's a large part of why we're shutting down. If this thing got away from us (we can't possibly know yet), a lack of isolation would mean every place that didn't isolate would essentially have an Italy situation on their hands. That's an insane risk to take.