It only really works for bootstrapped non-profits, and for projects that are entirely volunteer-driven. No VC would be able to invest in something like this (unless it's a grant like what YC does for non-profits [1]).
Even Mozilla Foundation [2] was spun off from Netscape, and heavily supported by AOL in its early years.
I guess most founders are really just motivated by the pot of gold at the end of the rainbow :/