If you have an elective health insurance system where people choose whether or not and when to participate, it implies this restriction.

Say you have private health insurance companies but don't allow them to prohibit members based on pre-existing conditions. Everyone will simply not get health insurance to avoid paying the premiums until the day they need it. That would make health insurance companies completely unviable financially.

This is why Obamacare both eliminated the pre-existing condition restriction and mandated people get health coverage. You can't have one without the other or you get the free-rider problem.

This is another reason why healthcare should just be universal. It doesn't work at all like an actual efficient market product.

If that sounds unfair to an insurer, that's great--now they know how we feel about it.

Insurers want to deny pre-existing conditions because they don't want to add already-sick people to their risk pool. They wouldn't have to, if the previous insurer was still on the hook for that diagnosis. But they'd never agree to that, because it exposes them to some of the same insolvency risk due to medical bankruptcy that some patients have to face.

Surely "what you can" should be relative to both your income and your need. We'd need to supervise the system to make sure people aren't taking advantage or else the whole system goes broke.

> into a common pool

We could also invest the money in the pool to make some extra cash and reduce what people need to pay in, we'd have to have an organization do that too.

> (only as much as you need)

How can we know what people need? We'd have to charge a token amount for office visits and medication so that people aren't frivolous with their medical visits, while perhaps guaranteeing an out of pocket limit in case of extreme illness. We'd also need some kind of system to verify that people are only taking what they need.

I think you just invented health insurance.

One way is like we do today -- highly-paid positions often come with high-quality insurance, which is (ime) fairly expensive and low-paid positions have less expensive insurance that is a bit worse (all this on average, I'm sure there are outliers).

We are in different pools today but I don't see how that's meaningfully different than everyone being in one pool if the individual pools are large enough and you can't discriminate the population of the pools.