Comment by jltsiren

In my experience, people are willing to contribute up to 10 hours/week to individual volunteer projects they care about. That may increase to up to 20 hours/week for a year or two when they assume a key role.

A full-time job takes a third of your waking hours. Then you probably need to spend another third on various maintenance activities, leaving you with the equivalent of a full-time job to spend as you see fit.

Of course, when you have a volunteer-run project, your priorities will be different from projects that people do for a living. You will probably focus on what the contributors find interesting or important, rather than what someone else might find useful or valuable.