OKCupid is owned by Match.com, I've never used OKC but it's probably part of the Match sales funnel and so if you average out the LTV of one conversion to a paid monthly subscription and distribute it out over X number of free users 5 dollars a year isn't outside the realm of possibility.
Blatant shaming and guilt trips aren't going to inspire donations from me. If you're treating your users like adversaries or tools you don't get to assume the moral high ground.
Bullshit. No way their average ad revenue per user is > 5 USD/year. Especially since OKC has a large non-US audience.