When the provision of a public good is financed by voluntary contributions, it is in the private interest of an entrepreneur that the firm collecting donations be subject to a nondistribution constraint.
Prediction: firms receiving donations to provide a single public good will be nonprofit, because of the self-interest of the entrepreneur founding the firm.
Everyone can anticipate that it would be optimal for the entrepreneur to contribute again if donations are too low (so they make smaller donations). Because of this, the entrepreneur needs a mean to commit to not making a positive contribution at the last stage. This can be done by making a sufficiently large initial donation (of time or money).