Luke Winkie writes on Vox.com:

Jen Glantz is there for women on the biggest day of their lives—for about $2,000 a wedding. The 31-year-old entrepreneur has been a professional bridesmaid since 2015, working dozens of ceremonies each year around the country. She's a dear friend for a day, not a wedding planner. Glantz says, “I'm not going to be able to pick your flowers or taste your cake with you.” Instead, she specializes in energizing the dance floor, distracting problem relatives, and above all, comforting the bride. “You're running around putting fires out. You'll clock 30,000 steps in one wedding.” Some clients have suffered a recent falling-out with a bridesmaid and need a quick fill-in, while others just don't have enough close friends.

About three-quarters of the time, brides ask Glantz to make up a fake name and backstory—she usually claims to be a friend from some obscure hobby. Glantz launched her company, Bridesmaid for Hire, in 2015 after serving as a civilian bridesmaid in her 20s for numerous friends. “That got me thinking that if I could do this for friends, I could do it for the wedding industry.” She now has a team of pro bridesmaids but rejects any applicants who emphasize how much they love to party. Glantz says of the job, “It's not a party, it's an emotional roller coaster.”

Source:

Luke Winkie, “Odd Job: ‘Professional Bridesmaid’ is an actual job,” Vox (12-6-19)