Good question. I spent the first dozen years of my career at large companies and led a mostly 9-5 existence while taking advantage of the free training and growth opportunities that existed at the time. In 2000, I started working at early stage companies and have been in startup mode ever since. The hours are long, the work is fun, and I find myself always learning something new every day, be it technical or otherwise. Three of the companies I've worked at have enjoyed successful acquisitions, while the others crashed and burned. Nevertheless, the lessons learned from these experiences and the friendships and contacts I've gained have proven to be very valuable, so I guess I'm... stuck in a rut.
I agree, there is more to life than work. I just haven't yet found what that is.
If work is what you enjoy doing I say keep doing it Just don't be a slave to it...
Anyway, you do choose to work this much. Not having time is still not a valid excuse in my opinion, you simply choose to spent it working (at least most of the time)