Most healthcare costs are at the end of our life, and we all die and often spend all we have, so the costs are fairly invariant i.e. you can never “save” $2k.
The ROI for better health is very odd to measure.
If you use dollars (for an economy) then the best ROI is to spend nothing once someone is of no economic benefit (i.e. the vast majority of healthcare spending is on the elderly and provides no dollar benefit to society, so economically most healthcare spending should be drastically cut).
You could also look at an integral of quality of life over time. However “past me” is really bad at caring about “future me”, and “current me” doesn’t care at all about optimising for “past me”.
Most people seem happy to argue that the amount that society should spend on them (or their loved ones) for health services is infinite (you can’t put a price on life), and the amount they should spend on the health services for others should be zero (those scabs should have made better life choices!)
Good luck trying to make sense out of spending $20 to save $2000!
