Billionaire investor Warren Buffett expressed support for adopting a single-payer health care system on Monday, arguing that it would likely do a better job of controlling runaway costs.

In an interview on “PBS NewsHour,” host Judy Woodruff asked Buffett, a longtime Democratic donor, how the United States should address the Affordable Care Act, commonly known as Obamacare.

Buffett qualified his comments by claiming that health care policy was “way outside [his] circle of competence.”

“With my limited knowledge, I think that [single payer] probably is the best system,” Buffett said.

Buffett’s support for a single-payer health care system, in which one government insurer covers the entire country, was based on the current system’s failure to keep rising health care costs in check. He noted that health care costs have risen exponentially as a share of the economy in the past four decades, holding back the competitiveness of U.S. businesses far more than taxes have.

“In almost every field of American business, it pays to bring down costs,” he said. “There’s an awful lot of people involved in the medical, the whole ? just the way the ecosystem works ? that there is no incentive to bring down costs.”

A single-payer system would likely “be more effective” at reducing those costs, he concluded.

There is abundant evidence to back up Buffett’s argument. Medicare, a single-payer system for America’s seniors and disabled workers, has a far better record of containing costs than do private insurers. Among other reasons, that’s because Medicare does not need to fund a marketing budget or compensate shareholders and executives.

The United States, virtually alone among developed nations without a universal single-payer system, has by far the world’s highest per-person health care costs ? and based on many key criteria, it nonetheless has worse outcomes.