Health care costs are constantly skyrocketing in the United States—and will likely get worse, whether from the usual escalating expenses or special cases like the dispute between health care companies, which could saddle many patients with surprise hospital bills.

All in all, it’s an unfortunate good business for crowdfunding source GoFundMe, according to Kaiser Health News.

People have used the site for many purposes, including public border wall funding and legal defense expenses for former Donald Trump fixer Michael Cohen.

But the big business of GoFundMe is now medical bills. Since the company’s founding in 2010, it reports having raised $5 billion. Of that, a third went to the 250,000 medical campaigns the site conducts annually. Simple multiplication suggests that the number of people who have sought help has run into the millions.

CEO Rob Solomon told Kaiser News that he had never realized the difficulty so many faced in dealing with medical bills. “We didn’t build the platform to focus on medical expenses,” Solomon said, but that is what people needed.

“Some progress has been made here and there with the Affordable Care Act, and it’s under fire, but there’s ever-widening gaps in coverage for treatment, for prescriptions, for everything related to health care costs,” Cohen said.

Those gaps can be significant. For example, bronze plans under the ACA have the lowest premiums and so are often the choice of those who are under financial pressure. But such plans only cover an expected 60% of costs, according to the federal government. People can find themselves having to pay thousands of dollars before insurance picks up the rest.