It doesn't need to be that way. If we had flattened the curve enough, it would have allowed time for treatments and a vaccine to be developed. By following the Sweden model going forward, it is entirely possible that 60-70% will become infected prior to a vaccine, but it didn't have to be that way. With more self control, we could have stretched this out until early 2021, when hopefully a vaccine will exist.
Of course, we have those who now want to go with the "well, what if there is NEVER a vaccine" argument. Which makes it much easier for people to accept the fact that we might as well open up, because it's never going to get better, so we're only hurting ourselves hoping for something to come along. And sure, it is possible that will be the case, but not according to what most scientists are saying. Most seem to believe that an effective vaccine will be in production by 2021, and eventually it will be readily available. I have yet to hear anyone with intelligence say that it is unlikely a vaccine will be developed anytime in the next several years.