Ordinary flu killed some 80k americans last year. Covid-19 seems to be ~20x as deadly as the ordinary flu, and spreading at least as fast if not much more. So if it becomes endemic, embedded in the general population, just as flu is now - then the next flu season will have 1.6 million dead americans. Most people would consider that this is a large and undesireable result; that worrying about such a result is reasonable, and that it would be imperative to try and prevent it from happening if we can.