There's still a benefit in insurance for routine procedures to balance costs between the young and old. (As long as young people are required to have insurance)
...but the fact that the median income of young people (at the beginning of their career, whatever it is) is much lower than old people, pretty much nullifies this. If you want to balance out the costs over a person's life, there are much better ways than making the coffeeshop barrista subsidize the middle-manager's health costs.
The reason this logic fails is because income and healthcare costs are on different curves but of similar (or far greater in the case of healthcare) magnitude.
Say you start out your career making $30K as a barrista and end up making $150K as a middle manager in your 60s. A single surgery can be $150-$300K and you're more likely to have them when you're older. Cancer patients can cost millions in a given year, again you're more likely to have that as you get older. I don't have the number for a diabetes patient off the top of my head but I think it's 10s of thousands a year.
The income growth curve is far shallower than the healthcare cost curve, and the healthcare cost curve is essentially unbounded whereas for most people income doesn't go all that high. Remember median income in the US is something like $55-$60K. Most people won't ever see 6 figures and if they do, they'll see the very low end of that.
