Dave Plowman (News) brought next idea :
And you might need the NHS for something serious at any time in your life.
Regardless of how much you have paid in. If you are unlucky. So absolutely
no different from unemployment benefit.

We all take a gamble paying in, some will need more back, some less -
problem is there are some who make a life choice of not paying anything
into the system at all, yet expect the same benefits as those who do
pay in.