Without belaboring the obvious: 80h/wk is over 13 hours each day of a 6-day workweek. Assuming 0.3h/day exercise (across the week) and 6h/day of sleep, you're left with 4-5h/day for everything else in your life. This is obviously a tradeoff you'd want to make iff everything else in your life is not something you want to allot any time.

Edit: This reminds me of a discussion a friend had with the partner at the white shoe firm where she worked at the time. The partner said "...friends, family, and outside interests are all important. But you have to decide between them and success here." Obviously a paraphrase; this was ~10 years ago.