For most people that's probably true. But I definitely know people that are just like that to the point that it's at least sustainable for them. They were absolutely brilliant, but kind of manic at times, and that's just how they worked best. They'd work for like 20 hours straight without eating and then come home, wolf down some food ravenously and sleep for 14 hours. Who am I to judge the schedule they chose?
Those people may actually exist. But it is easy to miss that they may indeed have pathological (hypo-)mania (and the occasional depression). Or that they take certain drugs. Or that their health indeed suffers. Or that they do break down after a few years.