1 out of 5 uninsured Americans live in a $75,000-a year household; from AEI:

There are 9.7 million uninsured Americans living in households making $75,000 per year or more, and this represents more than one out of every five uninsured (21 percent of the total). There are 8 million Americans without health insurance in households making between $50,000 and $75,000, representing 17.3 percent of the uninsured. With those two groups combined, 38.3 percent of Americans without health insurance (17.7 million people) lived in households with $50,000 or more of household income in 2008.
With $50,000 or more in household income, wouldn’t many or most of those 17.7 million uninsured be without insurance voluntarily? That is, couldn’t most of those households afford health insurance?