It seems like you're implying that these non-profit founders put a lot of weight in salary as a consideration to whether or not they pursue their vision. That's something I'd disagree with (though admittedly my opinion off is based off the folks behind Watsi).
The non-profit startups that are going to fit YC are going to be the ones that aren't in dire need of a market salary, who don't need the potential of a huge cash windfall to keep on grinding.
The sacrifices here will be made in the pursuit of 'success' (however you define that), and the pursuit of watching your organization be large enough to make a difference (these are also primary motivators of for-profit startups in my experience).
The non-profit startups that are going to fit YC are going to be the ones that aren't in dire need of a market salary, who don't need the potential of a huge cash windfall to keep on grinding.
The sacrifices here will be made in the pursuit of 'success' (however you define that), and the pursuit of watching your organization be large enough to make a difference (these are also primary motivators of for-profit startups in my experience).