I've been both of those people. I spent 5 years working every waking minute of the day; even if I wasn't at my computer, I was thinking about what had to be done next and constantly anxious to get back to it. I ruined several relationships and generally had a piss-poor life because of it.

Now, though, I work my ass off at my day job, I spend a couple hours a night and the weekends working on my startup, and I spend as much time as I possibly can with my girlfriend. I'm a much happier person, and I'm still making tons of progress in life in general.