@abundance
probably needs some expounding but there are essentially two stages here:
In the first stage the network determines the (expected) value a public good
In the second stage - once the public good is created and already has impact on the network - the network reviews the impact and reward the good (retroactively). This review can be recurring - with funding distributed based on milestones/percent of overall impact realized.
Between stages 1 and 2 you can put a team together and get investors or loans for your project. Investors (or banks) take a risk on your execution, and can get a portion of the retro funding (based on what you agree to)
diagrammatically it looks something like this: