Huh, you have a pretty different perception of what makes a thing hobby vs. work. For me, a hobby gives you a permission to get better - because play is an important part of getting better. Whereas at work, you're constrained by the context in which your work is embedded. For instance, when working on a hobby project, I can afford to do each piece of it right, to the best of my abilities - whereas at work, I have to deal with things like team velocity, time to market, list of features driven by sales instead of utility, etc. - all of which preclude doing great work.