> How does the concept of health insurance, risk pooling, etc., make sense if there are no lifetime maximums…?

You're right, it doesn't make literal sense. Though we use the term, health insurance, everybody is really talking about medical coverage, period, except for those trying to play semantic games (not pointing to you). Concepts like risk pooling can still be useful, but at the end of the day we're not really talking about insurance, but how to equitably spread the costs and benefits of rapidly advancing medicine.

Social Security is closer to an insurance scheme. Social Security is a deferred life annuity (a type of insurance instrument) that everybody is required to buy, except there's no middleman. Unfortunately, the last time we extended the deferral period to properly account for risk and cost was 1983. When Social Security originally passed it was assumed Congress would regularly change retirement ages; people in the 1930s knew how insurance worked, and knew full well that lifespans would continue increasing, but they failed to account for political friction in having to explicitly update the terms of the program. Other than military pensions, we didn't have much political experience with large entitlement programs (though it's possible the reason they didn't build in an inflation mechanism then is the same we can't do it today).

Medicare was patterned after Social Security, however like SS we don't properly adjust the age nor pay-in as lifespans have increased and medical costs soared; and advances in medicine and expectations of care evolve so quickly these days that I'm not sure its even possible as a practical matter, not while pretending it's truly any kind of insurance.

Health insurance is already a huge transfer to older generations (not that that's a bad thing). Medicare pays for older folks but it doesn't pay anywhere near the cost of the services that older folks receive. Prices are higher for everyone else to fill the gap at health care providers.

Health insurance is in many ways not even insurance, it's in many ways a price negotiation mechanism.

Anyway the whole system is overly complex, based off a tax credit from the 1950s, but the transition to a new scheme is nearly impossible while one political party is dead set against any improvement, especially if it might be perceived as a positive for the other political party, and also they have become so hyper partisan that they are not allowed to work with the other party in a bipartisan manner.

Huh I didn’t know that. I thought those on Medicare only got the bare minimum service that stayed within cost.

In that case, the upstream sources of why Americans accept this huge charade is going to keep on messing with even the best laid plans.

It isn’t a simple money in, money out system. You’re taking higher value money in one year, and paying out some money that’s worth less later (inflation)… while at the same time, you’re investing the pool of money you collected, and earning returns on that before you pay out claims - claims that you’ve already negotiated down in price. But by the time the healthier customers need to start making large claims, they’ve already both subsidized the claims of other customers, and made the insurance company more money than they’ll draw in claims.

It's a simple money in, money out system. Health insurance isn't like homeowner's insurance where the insurer accumulates and invests a pool of money in anticipation of occasional rare events like natural disasters that cause a spike in claims. Medical expenses across a large patient population are very predictable and there is no significant carry over of premiums from year to year. In fact, under the Affordable Care Act (Obamacare), it is actually illegal for most health insurers to do that. Any excess premiums collected must be returned to customers at the end of the year.