I don't know.

But if I understand correctly, the point of bringing up the Oregon study was that access to medical care doesn't seem to have a lot to do with it. At least not the incrementally better access provided by Medicaid programs.

I would certainly speculate that there is a bundle of ideas that contribute to it. Ideas about personal decisions being impactful, leading to things like less smoking and better diet, and even better life situations (which can presumably lead to a different relationship with stress).

Probably because the poor behave differently from the rich - they tend to overeat more, exercise less, smoke more and drink more.

Also any disabled person (who probably has other health problems that reduce life expectancy) is by definition poor (poverty is defined as low market income).

It is poverty itself that creates short term thinking that leads to those choices.

This is why poverty is expensive for society, and investment by society to eliminate it would be paid back and much more.

No it isn't. Again, please read the RCTs I linked to. One of them addresses this exact question.

All of the behaviors you cite could be caused by extreme stress, poverty, or threats to safety/well-being (rather than being a cause of poverty). I've felt it, and I've done it.