Non-profit does not have to be equated with near-zero-salary for employees. The cash in flow (the revenue part) for non-profit comes from patrons who are well-off and have desired to give away part of their surplus wealth. As the non-profit startup grows and shows results they can do rounds of funding from other patrons, institutions and government just like for-profit startups will do roadshows. The return of the investment is the positive impact they created on lives of disadvantaged people or future generation. The important thing to realize here is that for-profit and non-profit are not that different. Both have revenues, expenses, profits, return on investment, competitors, deadlines, talent acquisition, business plan, products, metrics, investor objectives and so on. The only thing changes is definition of profits and return on investment. There is a huge benefit in running non-profit just like for-profit organization.
I would highly recommend reading chapter on "Performance Philantrophy" from the book Richistan: http://www.amazon.com/Richistan-Journey-Through-American-Wea...