I know. Do you think those young realize this?
Everyone who thinks about it does.
That’s why health insurance is (generally) affordable to all.
The insurance is priced so that the price covers the outlay for the medical costs plus operating expenses, plus profit.
It is then broken down into age bands, with the price in each band reflecting the chance that someone in that particular band needing care.
Young people generally don’t think they are going to have much in way of medical expenses, and so they forgo the insurance. Usually, they are right.