Yes, the way I understood this is that customers can contribute to projects more easily. If you don't have any customers / users willing to pay then you don't get any money.
As for your situation, put a notice up on your project that you are willing to fix bugs / code new features for a fee? If these companies use your library they might be interested in sponsoring your work.
If they are not however, then I don't think there is a way to fund your development.
As for incubators etc., they are probably not all that interested in a BitTorrent implementation, considering how many are already around? Unless of course the library provided some value nobody else does.