I'm not sure how to respond to this. I don't think we should measure the value of a human life in purely economic terms. Do you really want to live in a society where we deliberately kill anyone who currently takes more out of the economy than they are putting in? This is what you are suggesting, isn't it? Because employing a strategy that lets the virus kill the old and the vulnerable is no different to rounding them all up and shooting them, you're just substituting the virus for a gun trigger. Also I italicised the word 'currently' back there because of course plenty of these people will have paid hugely into society over the preceding decades, and will have put in much more than they have taken out over the course of their lifetime. Think about for example people who fought to save your country in WW2. A strategy of 'they are now old so let's kill them' seems morally abhorrent.