You have mentioned a widespread fallacy. Along with monetary incentives there are a lot of another ones which are not less efficient.
BTW, read about USSR space program and how it's head engineer Sergey Korolev was motivated "non-monetarily". They have achieved launch of the first satellite (1957 Sputnik) and manned spaceflight (1961 Yuri Gagarin)!
I work without any compensation for the bitcoin community with my own time, own money, and own skill. And surely enough, I am not motivated by money.
Let's also note that the creation NBitcoin does not involve trading with parties, so money is not really needed for the project's scope.
Same thing with Sputnik, since the material was provided by gov and not by trade. But the result is that the project belongs to gov.
But, NBitcoin -my creation- is my property, open source, not the one of the government or any other.
If someone would say : "Now, NBitcoin belongs to me and you will work against some garanteed subsistance decided by me (in other word, more than what I earn currently)", I would not have put so much forces in the work, and the work that took 4 months to do would took 20.
What a shame of time and effort wasted. It would be a restriction imposed upon human expression.
No matter how legal it can be.
My labour and my wealth belongs to me, and I consider my responsibility to protect it from any elite or central planning.
And I hope that others will take such responsibility into their hands so I can trade with self driven, self supported, productive and authentic human. And not a bunch of whining bureaucrats not looking beyond their next pay check, wondering why "the world" goes bad because of "complex economic situation".