Ideally I would prefer to sustain myself from one of these projects. There are a lot of projects that are successful. Sure they aren't making a fortune, but they enough money to support their maintainers.
but they enough money to support their maintainers.
Are you sure?
I haven't done a survey but my guess is that the Open Source developers being supported solely by their projects are a very small fraction. But best of luck becoming one of the select few.
How do you make money from free software? Short answer --- you don't.
There may be a need/desire but there is no real "market" for Open Source.