The young subsidizing the old essence of insurance, as the young tend to be healthy. As compensation they tend to pay lower premiums. Thing is whether you force them in the pool or not, they're still subsidizing the old. I'd rather deal with 'free riders' by at least giving them the choice of buying insurance or being taxed for Medicare or something.
I would also allow companies the choice of taking high risks and pre-existings, with some incentive like tax credits for subsidizing their premiums. There is a big difference between a guy with an old football injury to the knee and needs a massage twice a month, and state 4 cancer. We could do this with national policies fairly easily.
I don't know how else to deal with high risk/pre-existings and 'free riders' other than to have a dual system that allows for some choice and doesn't mix two different types of health care needs and force square pegs into round holes.
You're only looking at part of the picture. The old tend to tone down their lifestyle a little. At this age, I wouldn't live through half the stuff I did when I was younger. Older drivers (to a point) tend to be better, too.
What does shift is the type of medical expense and the cause of the expense. I still look around in amazement at all the 'healthy' folks half my age who have had shoulder or knee surgery, etc. mostly sports injuries.
Bottom line is that an honest assessment of risk would lead to some level of coverage for an individual, and the catastrophic care plans covered the worst-case scenarios. That, thanks to Obamacare, is no longer an option, but would have balanced personal perception of risk versus cost. If a person is healthy, that would cover most of the major stuff, and leave them the resources they need to eat well and do the rest of that "healthy" stuff to avoid larger problems later.
Demanding that people be divested of resources forcibly without letting them assess their needs, real and potential, and allocate those resources as they see fit is totalitarian, and has absolutely no flexibility for individual situations. But forcing them to spend money on insurance that might have put new tires on the car will at least have them covered when they hydroplane into a bridge abutment, right?
All my young life I was told to "Grow up, be responsible!". I did. Now that I am there, I have some pencil necked pinhead two thousand miles away that hasn't been within a thousand miles of where live at ground level telling me to do things which go contrary to common sense, with the force of law behind them.
No wonder we're becoming a nation of snowflakes. Too damned much cognitive dissonance out there.
Under the current "health care" system post-menopausal nuns are required to carry coverage for contraceptives. That isn't covering people who might need some service, it is just a ludicrous abuse of power.