I hate this attitude that there's something wrong with that. It's perfectly possible to be a good engineer doing only 40 hrs a week.
Frankly this whole attitude is a big part of why we have a diversity problem, because only a small minority (over represented here on HN) want to spend all their time building software and this attitude puts a lot of people who weren't teenage coding geeks off joining the industry. It's actively harming the industry and I wish it would go away. If you individually enjoy coding for fun above anything else by all means go for it and enjoy your life, but stop trying to force that on the rest of us. There's more to life that just building software!