Two big incentives that you see in most human activities:
* build something for other people
* try to be recognized
Money is a tool to make society work, it isn't really what people live for. People inherently want to contribute to society.
When I didn't, it was a fun hobby. One that lead directly to my job, so there's another incentive for you. Enjoying oneself is also quite sufficient.
There's a significant and growing free-rider problem with open source software, but your not understanding why people do FOSS is on you. It's not difficult to understand.
FOSS, itself, is the necessary lego kit the entire web (and to a lesser extent mobile and desktop etc) rns on... are you suggesting that everyone go buy Coldfusion or ATG Dynamo? the 90's called and want their time machine back...
I honestly don't care that people work for free, it just saddens me that it takes so long for these people to realize how important financial incentives are. It is clear as day that this model rarely produces any financial results for the developer, even if people and companies are actively using and profiting from your work. That stuff seriously makes me wanna puke.
The reason why it doesn't work is because it violates a very basic business principle. You don't wait for someone to "give" you money for your product, because noone is going to do that. As a manager it is incredibly painful for me to go through the entire chain of command to give you money "for maintenance". Instead you should "take" it by making me wanna buy it.
The strawman part of your argument i will avoid, since it is a clear nonsensical trap.