By all accounts, Nye Bevan borrowed the idea from workers' cooperatives, in the South Wales valleys. The mining and steel communities had high rates off illness and the concept of "group insurance" was not long in coming to them. Health bills come in big lumps but workers, in general, are only "drip-fed" their pay. Anything which can spread one-off costs over a lifetime has to help.
Under the private system, the internet is awash with "folk remedies", health advice, weight-loss products, "detoxification" and all manner of quackery which, I might add, gets away with charging nearly the same rates as properly qualified medical practitioners.
Disclaimer:- Some folk remedies do work but I do not know which ones. I apologise, in advance, for lumping them in with quackery but it's just a list of "things which are not professional medicine".