Is this evidence of the 996 culture?
People who wish to master a skill on their own time are simply pursuing an intrinsic (/identity-based) goal: here, excellence in computer science.
"The 996 working hour system is a work schedule commonly practiced by some companies in the People's Republic of China. It derives its name from its requirement that employees work from 9:00 am to 9:00 pm, 6 days per week"