I thought that some of the discussion in this thread would be better served by drawing attention to an often missed distinction: nonprofits =/= charities.
In many countries including the United States, it is perfectly possible to operate a non-profit corporation without registering as a 501(c) charity. You just need to find a revenue stream that doesn't consist of donations for the most part, because only charities can accept tax-deductible donations. For some non-profits, of course, this is a non-starter. For others, it can be very natural. You sell products or offer services like any other company, but you charge fees that cover the cost and not much more. You also structure your corporation so that the people who run it are "members" rather than shareholders and any surplus income is always reinvested. (That's why YC didn't get any equity from Watsi in return for their investment/donation. A non-profit corporation doesn't have the concept of equity to begin with.)