> You're good to live off that and work on that project full time.
What if they don't want to work on it full time? What if they don't feel like they are tied to their work or obligated to serve "customers"?
Software is not just about creating tools for a trade. Software is also self-expression and leverage for creating other things of worth.
Your issue is with FOSS developers who are amateurs (in the good sense of the word) and thus "fail" at supporting themselves and their "customers" with their work.
This is a not only an incredibly myopic view - I really don't even want to imagine what would be the state of the industry if FOSS projects like GNU, Linux, Apache and many others who are successfully funded didn't exist - it is also one that serves only the big corporate world that you think "should be paying". It reeks of a Protestant worldview that acts as something is only worth doing if you can make money off it.
Anyway, your problem is with "amateurism" in the industry, not with FOSS. For every "hassle" you find in FOSS projects, there are plenty of others who are successfully managed, with developers who know to answer "This is Free Software, but it does not mean you are entitled to free work or my time. If you want me to solve a problem you are having, you have to pay for it".