For more and more Americans, vying in a popularity contest for a limited supply of funds and sympathy may be the only way to pay the doctors and stay afloat. House Republicans passed a bill last month to replace the Affordable Care Act, or Obamacare. As is, the Congressional Budget Office estimates, it would leave 23 million more Americans uninsured in 2026 than under the ACA. Even a law just resembling the bill is likely to raise the cost of health care for older and sicker Americans and for those with preexisting conditions, bolstering the medical crowdfunding business.

The industry still represents just a fraction of the hundreds of billions of dollars Americans pay annually out of pocket for health care, said Saper. Medical crowdfunding is "highly, highly scalable and has a ton of runway," he said. "The growth rate of the industry is showing that this can absolutely be an impactful safety net for a lot of individuals and communities to help each other."

The remarkably named Producing a Worthy Illness: Personal Crowdfunding Amidst Financial Crisis, a study published this year by the University of Washington/Bothell, offers a striking perspective on some of those communities. Personal medical campaigns on GoFundMe were likelier to come from people living in states that chose not to expand Medicaid under the ACA, preliminary results of the study showed. Fifty-four percent of 200 randomly sampled campaigns last year came from those states, though they are home to just 39 percent of the U.S. population. Trumpcare would sharply curtail Obamacare's expansion of Medicaid.

"We had a huge number of campaigns from Texas, which is often recognized as the state where it's most difficult to qualify for Medicaid and other public insurance," Professor Nora Kenworthy, co-author of the study, said. "A lot of the campaigns are really using GoFundMe as a safety net," asking for "help with lost wages, help getting basic health-care services and support."

Most medical crowdfunding campaigns are a far cry from Taylor Swift's $50,000 gift on GoFundMe to a young girl with aggressive leukemia, or $1 million in donations for a mother whose cancer returned when she was pregnant with quadruplets. "Often, funds people are raising are for a huge range of costs that go along with care, like travel to the place where you will get care, because insurance doesn't really cover that," said Indiegogo's senior director of social innovation, Breanna DiGiammarino. In the future, more fundraisers will likely seek to cover premiums and deductibles rather than the cost of care itself, she said.

"Crowdfunding is being treated a little like crowd-insurance now," said Daryl Hatton, CEO of Canada-based crowdfunding platform FundRazr.

Yet crowdfunding's business model is a poor fit for the gargantuan, mundane, never-ending health-care costs of many online campaigners. Some get just 10 to 20 percent of what they ask for, said Jeremy Snyder, a health sciences professor at Simon Fraser University in Canada, where the need remains even with a national health-care system. Snyder's research, which includes analysis of ethical issues raised by medical crowdfunding, has focused on people seeking funding for cancer treatments on Canadian crowdfunding sites.

And, of course, in the U.S. as in Canada, some campaigners get less than that, or nothing at all. Slightly more than one in 10 health-related online campaigns reached their goal in the NerdWallet report. The Bothell study found that 90 percent of the 200 GoFundMe campaigns didn't reach their goal, and that, on average, fundraisers got 40 percent of what they asked for. That doesn't sound like much of a fix to Snyder.

"Is this something that is going to be a solution to a lack of health insurance?" he said. "Absolutely not."

One reason for the discouraging statistics is that while most of the campaigns are ordinary—and no less urgent for it—it is often the extraordinary ones that do best.