I didn't say it was the "right" thing to do, only that 20-somethigns can do it because of their current lifestyle. The post referenced in your comment is basically a guy who realized that while he can operate in this way, he shouldn't.

Even if you're fresh out of school and have no kids, job, or friends that you care to spend time with, you probably shouldn't be coding 80 hours a week, even if your body and lifestyle permits it.