The perpetual inner turmoil for talented engineers :). I accepted a while ago that there's more to life than coding and career, so I don't do much outside of work - 40-50 hours a week of engineering is enough for me. But I try to focus on getting the best job possible that fits what I like to do.
Obviously spending 20+ hours a week on interesting OSS is going to get you more interesting roles over time, and generally OSS stuff is way more fun because you can pick what interests you. But you have to decide if it's worth the cost - do you really want to spend 60 hours+ a week just doing coding / engineering? Maybe you do, but in that case you'd probably be doing it already.
Obviously spending 20+ hours a week on interesting OSS is going to get you more interesting roles over time, and generally OSS stuff is way more fun because you can pick what interests you. But you have to decide if it's worth the cost - do you really want to spend 60 hours+ a week just doing coding / engineering? Maybe you do, but in that case you'd probably be doing it already.