The reasons for the lockdown were discussed by the Winton Centre (University of Cambridge) here https://medium.com/wintoncentre/how-much-normal-risk-does-covid-represent-4539118e1196
. It shows the relative risk for Covid19 for different ages and shows that "the Covid risk follows a similar pattern as the background risk". This is not to say that the people dying of Covid would have died this year anyway:
Winton Centre wrote:This suggests that COVID-19 very roughly contributes a year’s worth of risk. There is a simple reality check on this figure. Every year around 600,000 people die in the UK. The Imperial College team estimates that if the virus went completely unchallenged, around 80% of people would be infected and there would be around 510,000 deaths.
So, roughly speaking, we might say that getting COVID-19 is like packing a year’s worth of risk into a week or two. Which is why it’s important to spread out the infections to avoid the NHS being overwhelmed.
This is important because it accepts that we are not gods. However much of a civilised society we regard ourselves as we cannot make this virus go away.
As the discussion continues:
there will be substantial overlap in these two groups — many people who die of COVID would have died anyway within a short period — and so these risks cannot be simply added, and it does not simply double the risk of people who get infected. It is crucially important that the NHS is not overwhelmed, but if COVID deaths can be kept in the order of say 20,000 by stringent suppression measures, as is now being suggested, there may end up being a minimal impact on overall mortality for 2020 (although background mortality could increase due to pressures on the health services and the side-effects of isolation). Although, as we are seeing, at vast cost.
We didn't keep it to 20000, so far around double that by current measures. However there is indeed a vast and increasing cost in the side effects of isolation. People whose underlying condition cannot but be made worse and whose lives will be shortened, with significantly decreased quality of life.
The real difficulty is how to end the fear. If only the effort spent on this virus was spent on avoiding heart disease https://www.bhf.org.uk/what-we-do/our-research/heart-statistics
for example, many more lives could have been saved. Of course we cannot afford to spend that on every killer disease - because the social effects of the economic impacts would be too great. We had to do this not (as the propaganda said) to save lives, but to ensure that our health service did not collapse.