Not a matter of "if" but "when"
Go back and look at those flattening the curve charts. The area under the line, that is the number of people needing a hospital visit. The area (the total number of people) is the same. If we did nothing this would be almost over with now. A chunk of those people would now be dead due to medical overload. As we flatten the curve, it just delays the inevitable. And the world sucks for longer. So RAISE the curve (but still in the medical capacity) and the end date will come sooner. In the end the same number are affected, same final result, just get it done sooner.
This argument is false. There are many diseases to which we have no natural immunity which have simply been "contained". Ebola, SARS 1, the Black Plague come immediately to mind, but I'm sure there are many others.