You miss the point. "10x" doesn't mean working 2-3x longer than everyone else. If that's necessary, bad news, you're not a 10x coder. You're just an above average workaholic.

Of course, and hopefully he does. Working double the hours in a job you don't like would be awful.

I think most of us would accomplish 3 or 4 times more than we do given an additional 30+ hours of peace and quiet without distractions or external commitments, so I'm really asking if he's actually accomplishing more than any normal 1X developer would in his circumstances. I strongly suspect he's very fortunate to have a job and a family who support his choice to spend large amounts of time doing what he wants to do.