I find it strange that individual persons still think of getting into open source as a profession. If the motive is to share something you built with others wit

I find it strange that individual persons still think of getting into open source as a profession. If the motive is to share something you built with others with no expectations (except attribution, maybe some bug fixes, a user community) in return, then by all means you should get into open source. But what rational person would think that working on open source full-time is a sustainable way to make a living. Imagine a doctor who only does pro-bono consultation. Would they be able to make a living?