80 hours still leaves over half his time for eating, sleeping, the small amounts of physical activity which are realistic, and small amounts of human interaction. It simply does not leave time for leisure or to unwind, but as I said previously if your work is what you would do with your leisure time then that's not an issue, as there is nothing to unwind from.
Now I have only encountered this situation for a brief 3 month project which I wish had never been finished. But this type of dream job type situation does exist, and I don not believe is unhealthy, unless you have some sort of family to maintain also (it doesn't really leave enough time for a healthy family life).