We won’t know until we know, exactly how deadly this new virus us. It might not be as deadly as it initially appears. But it is hospitalizing a lot of people, even if they don’t die, and that is where the real strain is.
But for the sake of argument, lets say that this virus has effectively the same effect as the seasonal flu does. That is on top of the season flu, automotive deaths, and drug and alcohol ODs. Plus, without a vaccine no one has immunity, so it will continue to spread and hospitalize people until either: a) we slow its transmission, or b) a vaccine is developed and enough people take the vaccine (if I recall, you need around 90% of people to be vaccinated for there to be effective herd immunity).
I don’t like these stay-at-home rules anymore than anyone else (in fact, I really hate it), but these rules appear to be having an effect on slowing transmission, and the faster we can slow it down, the faster we can get back to normal.