Sorry, I am aware of this, I worded my comment incorrectly. What I meant to say is that one will be unable to ask for money for a ~different license~ to my contributions, becuase my contributions will be under the copyleft license, and I will not sign any agreements that give the project maintainers rights to license my contributions under a proprietary (Non open source) license. Yes, anyone is still free to ask for money for copy left code. But it is still copy left, and as such, the license goes with it.

Apologies for my poorly worded comment!