Scale AI’s Lucy Guo, world’s youngest self-made woman billionaire, says working 9 am to 9 pm is ‘still work-life balance’

Lucy Guo, the 30-year-old entrepreneur and co-founder of Scale AI, believes that working from 9 a.m. to 9 p.m. still qualifies as “work-life balance.”

In a recent conversation with CNBC Make It, Guo explained that long working hours do not necessarily eliminate personal time if structured properly.

“9-to-9 Is Still Balance”

“9 a.m. to 9 p.m., to me that’s still work-life balance,” Guo said. “At 9 p.m., you can go to dinner with your friends. You can invite them to a potluck. You don’t need to sleep from nine to nine—that’s a ridiculous amount of sleep.”

She further clarified her routine, pointing out that from 9 p.m. until 2 a.m., there’s still plenty of time for social activities. “Then you sleep from 2 a.m. to nine, which is seven hours—that’s more than enough.”

A Lifestyle Fueled by Long Hours

Guo admitted that her schedule sometimes stretches even further. She often works until midnight, then heads out with friends until 2 a.m., before waking up early the next morning to exercise.

“My genetics mean that I don’t need to sleep that much. Thank you, Mom and Dad,” she joked in a conversation with Metro.

Despite the relentless schedule, she does allow herself one partial day off during the weekend. On Saturdays, she takes time from noon to 6 p.m. to socialize before diving back into work.

Echoes of the “996” Culture

Guo’s approach to work mirrors the controversial “996” work culture that originated in China—referring to 9 a.m. to 9 p.m. shifts, six days a week.

The model has often been criticized for its negative impact on health and well-being, with activists labeling it a form of “modern slavery,” according to Wired. Despite backlash, the culture has influenced many Silicon Valley startups, particularly in the fast-moving AI sector, where grueling work schedules are becoming the norm.

Scale AI and Billionaire Status

Guo co-founded Scale AI alongside Alexandr Wang, the world’s youngest self-made billionaire. The company, which provides AI data labeling services, reached a $25 billion valuation in April 2025.

With a 5% equity stake, Guo’s net worth climbed to $1.3 billion, earning her the title of the world’s youngest self-made female billionaire.

Sacrifices Behind Success

Reflecting on the demands of building a startup, Guo said that long hours are almost unavoidable for founders.

“In general, when you’re first starting your company, it’s near impossible to do it without doing that [996]. You’re going to need to work like 90-hour work weeks to get things off the ground.”

However, she did note that those unwilling to commit to such a schedule could consider investing instead of founding a startup. “If you opt to start a tech company, you’re gonna be working those hours in the beginning,” she emphasized.