It's pretty common for people in SFBA to work 10 hours per day. Something about signaling that you're eager and a team player and want to advance etc. 8 or 10 hours doesn't particularly matter. My point is that even in some of the most competitive markets in the world, people do just fine with doing a full day's worth of work, then going home and having a life.
OP seems to be under the impression that this is somehow not possible.
The trend among engineers of doing a full day's worth of work then going home and working even more on side projects, open source, or whatever is a whole 'nother bag of worms. I'm not sure why we do that. You wouldn't expect a marketer to go home and do some marketing in their spare time. Or a business person to make some slide decks for fun.
Us engineers are weird.
edit: Why is this getting downvoted? Is it really that unimaginable on HackerNews that one could work full-time and still have time for hobbies, friends, and family?