There's a nuance to asking about cost-effectiveness for nonprofits that doesn't exist for for-profit corporations -- and that is that a nonprofit can be wildly successful by every metric
except helping people.
There are charities who take in millions of dollars, keep some, and spend the rest to send bibles to Africa. By every measure, they're "killing it": they have a well-paid staff, a happy donation base, and they send out a heckuva lot of bibles. It's an easy business model to copy, and an almost-guaranteed smash-hit in terms of getting returns on investment. But, here's the rub--do you think there's any evidence that sending people bibles increases their quality-of-life?
Basically, I'm hoping here that PG is getting into the nonprofit sector because he wants to help people--not just to become (more) rich by looking like he's helping people.