if you're a worker, then mostly yes. Ideally, self-fulfilling goals that require those extra 40-60 hours you're giving to a company then can be diverted. Not everyone can work at ChangeTheWorld corp for their day job.
Part of it is that, in general, there aren't great options to spend 10 or 20 hours/week--or, really, 700 or so hours a year doing interesting work for someone else on your schedule getting paid at full-time professional salary levels. You're not available when needed. You're not keeping current probably. Even if I could do some part-time consulting on what I currently work on, I'd become much less interesting to hire pretty quickly.