[laci27]

You're right. Like all things in life, one should use common sense when interacting with the world. No one (i hope) wants to spend their budget irrationally. So in your example, I would let the doctor decide if that $100 is spend better on curing rather than preventing. And that 1% reduction you came up as an example is not 1% for the entire population, it may be 1% to me and you, but maybe 50% for someone older, or with a specific condition...