Was slaving/living at work worth it?

I constantly see so many co-workers, and old co-workers that slave at work. They work 12 hour days; when they are at home, they are constantly checking e-mail, or doing something after office hours.

I was never this type of person, and from what I have seen first hand is most of the time all this hard work does not pay off like the person had hoped for. Maybe they get a 5% promotion, or whatever it is they are going for. I have also seen, more often than not, they do all this work for them to simply quit, get fired, or laid off.

My question is, for those who have put that much time and effort into work, regardless whether it was required or not, was it worth it in retrospect? Do you wish you ever spent that time doing something else (time with family, friend etc)? Did it pay off, and you got exactly what you worked for?