Here is a link to a piece which contains multiple sources about the efficacy of lockdowns

https://www.reuters.com/article/uk-factcheck-lockdowns-idUSKBN2842WS

A study which looks at deaths in Scandinavia

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3616969

Another study about how lockdowns in Europe saved millions of lives.

https://www.nihr.ac.uk/news/large-scale-lockdowns-in-europe-saved-millions-of-lives/25046

A look at the question by a fact-checking website

https://fullfact.org/health/can-we-believe-lockdown-sceptics/

I could go on but I'll stop.The question you have to ask is this, would there have been more deaths without lockdowns?

The answer is obviously yes. Without mitigation, the deaths would have been astronomical. How old the people are is irrelevant. A death is still death, whether, they're old or not. That doesn't diminish the seriousness of the disease, nor does it mean that those beneath 65 won't suffer long-term health implications from catching the virus.

You're more than welcome to write your own piece about why you believe lockdowns don't work.