Pepole under 50 are already semi-immune to CV19 becuase of their low susceptibility and death rate ! So would you NOT take an immunised population off lockdown !?
It's still the kind of rate of death that if scaled up to everyone being infected means fucking loads of people die young, not to mention the ones that are have some symptoms and a horrible time and are maybe permanently or at least long term affected.
Just because people under 50 have a lower chance of dying, it does not mean they have any less chance of being infected or (and this is the important bit) that they don't pass it on to people who have a greater chance of dying from it.
Still replying that you are talking bollocks.
Maybe read some of the replies to the first couple of times you've suggested this.