The problem is you're trying to reduce a moral question to one of simple economy. Money spent on healthcare is not an investment, we don't do it on the understanding that the patient will put more back into the state's coffers than their healthcare cost. We do it because we all understand that allowing someone to die early or suffer a lower quality of life when we can do something to change that is deeply immoral.
It is, in my view, entirely right that we do this. I do not want to live in a country that views people as nothing more than a resource.
And it's not the case that we can't afford to do this. We are constantly being told that we have no money and have to make cuts. So we cut public services like healthcare, mental healthcare, drug and alcohol treatment, unemployment benefits, disability allowance, police budget, defence budget. Cut cut cut, we have no money!
But when the people voting for these cuts need some money to bribe a bunch of terrorists to keep themselves in power, they can find it. When the seats in parliament are getting a bit tatty or Buckingham palace needs a lick of paint, they can find it.
This is not a question of money, it's a question of priorities.