Competent budget analysts know that the long-term budget problem is a health care cost problem. If U.S. per person health care costs were comparable to those in any other wealthy country, we would be looking at huge projected surpluses not deficits. Because health care costs are rising rapidly in the private sector, it means that the public sector programs that pay for these benefits (most important Medicare and Medicaid) also have rapidly rising costs.
If Medicare and Medicaid are lumped together with any other programs then the combination of Medicare, Medicaid, and the other program will be the cause of the deficit. For example, the categories of Medicare, Medicaid, and foreign aid explain the vast majority of the projected increase in the deficit over the next quarter century. Similarly, the combination of Medicare, Medicaid, and school lunch programs also explains the vast majority of the projected increase in the deficit over the next quarter century.
Robert Samuelson throws in Social Security as the third program so that he can tell readers:
"America's budget problem boils down to a simple question: How much will we let programs for the elderly displace other government functions."
Social Security does not in any honest way since it is fully financed over the period in question by the designated Social Security tax. But Samuelson does not feel bound by such details.
Of course there are easy ways to prevent health care costs from bankrupting the country, most obviously by taking advantage of the lower cost health care available in other countries. But, Samuelson never discusses such possibilities, focusing exclusively on cutting benefits on which the vast majority of retirees depend.