I suspect the "must work 24/7" thing is probably rooted in the fact that some folks are just like that and those folks are often crazily successful. But I think the inference that high number of hours worked is the thing to shoot for isn't really accurate. Some folks don't need a lot of sleep. Some folks can focus for long periods. Someone who has both traits may well be brighter than average.
Their phenomenal success isn't necessarily rooted in any one thing. Putting in the hours if you aren't that bright and actually need more sleep may be a recipe for disaster instead of a recipe for success. However, people like Bill Gates do tend to work crazy long hours. You can't ask to be born with his brains -- you have whatever brain you have -- but you can try to emulate his work habits and hope that's the most important piece. But I see no reason to believe it is. Perhaps long hours are a good idea. I just have yet to see good data which proves that. I have seen more data that for most people job performance improves if they cut back their hours and are working when fresh and focused.
Are they? What if you just don't notice the unsuccessful ones; they're at home spending ten hours a day drawing pictures of butterflies, or they're down at the gym obsessively lifting heavy things over and over again, or any one of a number of other obsessive activities that don't bring success.
