To an outsider, Billiejo Mullett is someone who has her head firmly screwed on. She’s smart and educated — a registered nurse who works for a medical insurance provider — and balances her career with a busy family life.

In many ways, Ms. Mullett, who lives in Minoa, N.Y., seems to have things figured out, which is why she is still reeling from a life-coaching experience she describes as a “pyramid scheme” that took tens of thousands of dollars from her.

“I’m an intelligent human being,” Ms. Mullett, 46, said. “We all think that it’ll never happen to us. That’s the really scary part.”

She is part of a growing cohort speaking out about the opaque underbelly of life coaching, an unregulated industry with an often-hefty price-tag, and a significant cost reaching far beyond funds spent.

With early roots in the late-20th-century pull toward self-improvement, life coaching broadly encompasses a program of goal-setting and talk-therapy-style sessions aimed at improving an individual’s circumstances and well-being.

Business is booming. The International Coaching Federation, the world’s largest nonprofit coaching association, estimated that the industry was worth $4.6 billion in 2022 and that the number of coaches increased 54 percent between 2019 and 2022. Because the industry lacks standardized accreditation, it’s most likely larger — one of the dangers of life coaching is that anyone can claim the title of life coach.