Robert Jenkins’ first job as a certified plumber was a dream. After a four-year apprenticeship, during which he rotated among four companies, he was hired by a local plumber with a reputation for good pay and a great culture.

“It was great,” he recalls. “Pay was good, and they supplied trucks and tools, at first.” Jenkins made about $40 hourly servicing small businesses and homes around Eugene, Ore., with trucks and tools provided. A few months after he started, Jenkins, 36, saw the company raise everyone’s pay across the board to $45 an hour. That’s when the trouble started. Jenkins says the company stopped supplying tools for its workers: “I was told we get paid enough to buy our own tools,” he said. It’s legal in Oregon for companies to make workers buy their own tools, as long as they make over minimum wage. But this was a change to Jenkins’ working conditions, and he felt cheated. He recalled one job that would have required him to buy a press gun to join pipes together—not a cheap outlay. “I buy a lot of my own tools anyway, and some of the biggest ones are $4,000, $5,000. I’m not going to drop that just for a company to take it from me,” he said.

Jenkins also clashed with a coworker, who, in Jenkins’ recollection, was frequently rude and belittling to junior colleagues, going so far as to curse them out in front of peers. When Jenkins complained to the company about the problematic employee, he was told the colleague was a high earner and effectively untouchable. Jenkins told Fortune he was “getting less and less happy,” and his “quality of life was getting destroyed.”

So despite having just been promoted, Jenkins quit. “I realized, I’m at one of the best-paying companies in the area; they have the best reputation; and that if I want something different I have to do my own thing,” he said.

Jenkins is part of a trend: Payroll processor ADP recently published research showing that people who are promoted are more likely to quit than people who aren’t. It’s a surprising statistic in a job market in which promotions, overall, are rare: Just 4.5% of workers are promoted within two years of being hired, making it much more likely that someone will quit for a different job than advance at their current employer.

“We don’t see a lot of promotions, and we don’t see a lot of development,” ADP chief economist Nela Richardson told Fortune. “You’d think in a tight labor market, it would be different.” There are many reasons people leave their jobs, even after getting promoted. ADP’s data does not specify whether promotions cause workers to leave. It’s possible that many, if not most of them, would have left anyway, since the qualities that can make someone promotable—including being ambitious and aggressive—can be at odds with corporate loyalty.

Less money, more problems

Then there are the promotions in name only. More than a third of offered promotions came with no raise, according to a 2018 survey by staffing firm Robert Half, while more than three-quarters of workers in a recent JobSage poll reported being asked to take on more responsibility with no added pay—a sure recipe for resentment.

And even a raise on paper, when all is said and done, can turn out to be much less than it seems. Often, workers are bumped up to a management or salaried role only to learn that they’re no longer eligible for overtime, commissions, or other perks that they had in their lower role, and that they’re actually taking a pay cut.

Money issues aside, moving up in an organization can also reveal broader cultural problems, as it did for Jenkins.

“One of the reasons I was at this company is their culture was pretty good,” he told Fortune. “Fifty percent of that is already proven to be not true—they’re making people pay for the tools they need for their job.” Seeing his rude coworker commended in meetings for his attitude sealed the deal, Jenkins said.

“At that point, I realized, it’s not going to get fixed,” he said.

He struck out on his own five months ago, and, though his responsibilities have increased as a sole proprietor, he said he’s now earning roughly his previous income.

“It was a big change to be also the person who talks to customers, pays all the bills. Dealing with the name change, making the LLC, that was a change,” he said. “But was it worth it? Absolutely.”

The experience also gave Jenkins a taste of what it means to provide a good working environment—which should be useful, since he hopes to hire an office manager and one or two plumbers in the coming months.

“Being part of the trades, our stigma that we have is that we work, work, work, and [culture] doesn’t really matter, all that matters is the work. I’m glad that the idea is changing, that working conditions have to be good for the employee,” he said. “I hope I can provide that.”