America’s extremely wealthy population is bigger than ever. And their money is supporting jobs for an increasing number of low-wage workers.

Also called “wealth workers,” they cut, clean and color the nails of rich people’s hands and feet. They rub and stretch rich people’s bodies. They help rich people exercise and become stronger. But the workers who provide this manicuring, massaging and personal training often earn very low wages.

Mark Muro is a researcher at the Brookings Institution in Washington, DC. He explains that people with extra money are willing to pay other people to do services for them -- whether it’s teaching them yoga or walking their dogs. At the same time, Muro says, an increasing number of people “really need this sort of work.”

But he notes that the country is losing middle-wage work -- what Americans might call “traditionally more solid or dignified.”

Personal care and services jobs are the fastest growing part of the job market for non-college-educated workers, the U.S. Bureau of Labor Statistics reports. They are expected to grow by 17% in the next 10 years.

The Brookings Institution adds that the number of manicurists and pedicurists doubled between 2010 and 2017. Exercise trainers and dog walkers increased at up to three times the rate of employment.

Muro says at least 3 million people in the United States currently do this type of service work for the rich. Wealth workers are more likely to be women and Latino. They often do not have a college degree. And they may work several jobs providing services to people who have more money.

“Our concern is not so much that the jobs exist, but that because of the way we structure work in America, they're not…good jobs. They really don't pay that well,” Muro says.

These workers are among the easiest to use unfairly. They rarely have sick leave, vacation days or savings to support them when they stop working.

But the jobs do offer something for new immigrants. One-third of workers in the U.S. are in the so-called gig economy, about 10 percent of them full time. The rest are part time, picking up gigs -- such as driving for Uber -- to add money from another job.

“I think it’s good for the economy because these are people who need those jobs and demand is the greatest creator of labor power for working people,” says Louis Hyman. He is the director of the Institute for Workplace Studies at Cornell University.

“The question is not how do we get rid of the gig economy, but how do we marry that with security? And it's not just a question for gig workers, but for all low-wage workers in America.”

Hyman says one answer to the problem could be to set up a system of private accounts for each worker. Every time someone provides a service, a dollar goes into their health care account, and a dollar goes into their savings account. That way, says Hyman, workers have an easy way to build financial security.

Mark Muro is also concerned about the health of American society. Service jobs often show the difference between the wealthy and the poor. That difference “will produce a lot of dissatisfaction…among the bottom half,” Muro says. He urges that work serving others be taken seriously and respected. “Let’s ensure these are dignified jobs,” he says.