I grew up seeing what poverty and lack of opportunities does to people, and I was determined to break away from that.
I got a job at a startup by sheer luck, and it completely changed my life. Heck, I was not even doing 996, I was getting up at 7AM and going to bed at midnight EVERY DAY including Sundays.
When I was not squashing tickets at a 2X rate than my European coworkers, I was learning new things, trying out new projects, writing blog posts for the company, doing customer support. I didn't care.
So yes, I agree now (from a privileged position) that 996 might be unhealthy in the long run. But let's not gate-keep or be naive enough to understand that some kids will need to put that effort if they want to make a difference. And yes, ideally the world would be fair and everybody should need only 40hs/week to make a living, butt that's a fairy tale.
If you're a young ambitious above-average person, and you're going to listen to people claiming this is "bad", please also compare your to their privileges: race, geographic position, net worth of your family, etc...