This 996 culture also exists in Taiwan (a democracy). Hard-work is a core part of Chinese Confucian philosophy (as is competitiveness). Many of my Chinese & Taiwanese coworkers have told me they emigrated overseas to US and EU just so they can work less (while still working more than everyone else in the company).

While slavery is forced labor, 996 is more about people trying to get ahead. During my wall street days, I elected to work 8 am - 2 am, 7 days a week for subpar pay, all because of future potential rewards. Many of my peers dropped out due to the pressure and didn't stick around for the big payoffs. If you interview them, no doubt they would consider themselves "slave labor."