the lockdown has not been put in place to save lives. It just hasn't. It's about resources
Why are resources important? Clue, it begins with L and rhymes with hives.
What resources do you think they are trying to protect that don't relate back to saving lives? Not just with reference to Covid but with reference to the economy going forward and the loss of lives relating to economic collapse.
You are correct that lockdown is not about individual lives so much as the wider picture. Some people don't seem to grasp that and think that govt advice is reliable in assessing every aspect of your own risk. It isn't, they just want to keep general transmission down to a manageable level.