A non-profit dating platform probably means you don’t charge much- which initially seems good, but it probably also means you’ll attract a bunch of users who aren’t serious because they have nothing at risk. So the people who are seriously looking for a relationship will be lost in all the casual users. Sure, you could make people deposit a bunch of money to prove they’re serious but you’ll lose all your users.
If you can figure out how to select people seriously looking for a relationship without becoming a pay to play app then it would be popular. But so far nobody knows how to do that. Or maybe someone does know but they won’t do it because there’s no profit in it.