Yes, of course a certain amount of private rented accommodation is needed.
But why does this have to be provided by private landlords?
Why couldn't it be provided by the government, for example?
(This is a radical idea, but one thought.)
If the government gradually bought back all of the rental houses in the UK as they came up for sale, and limited buy-to-let purchases, then we would eventually get to a point where there would be no private landlords at all (or very few).
There would be only affordable houses available to buy and live in, or houses available to rent from the government, on a sliding scale (the cheapest end of which would be council housing for people on benefits of course).
Yes this is a socialist view, and would require a radical overhaul over many years, but why shouldn't it work? - it would free up so many houses to buy, and enable so many people to have a home.
If you believe that everyone in the UK should have the opportunity to own one home in which they live (which I strongly do), then this would be an option to provide for those who want to rent AND free up affordable housing to buy and live in.
People do not need to invest in property. There are many other ways to make money. Homes are for living in, and everyone should have one.