Firstly, excellent analysis...

Secondly, take heart! If you look at it the other way, then 80% of people are sharing the love, which sounds better. (It also reinforces this intuitive feeling I've got about the 80:20 rule - this ratio seems to crop up all over the place, although here it might only be an artifact of the specific bins you've created.)

Also, 20% of people being utterly socially selfish is actually half of what it is in mainstream society - at least if you look at charitable giving as an indicator of how selfless people are towards generalised others: 39% of people in the UK didn't give to charity last year - source.

Thirdly, I hope this gets utopioned,

And fourthly, but do I hope that because I've got your best interests at heart, or because I know I'm going to get a fatter pay-out for myself in terms of curation rewards...>? 'Sharing the love' isn't necessarily an indicator of a 'pure motive' either!

Very very interesting! Thought provoking...