How much of Ripple was pre-mined?
Ripple isn't mined at all, it's entirely been allocated at inception and distributed by giveaway / subsidy / founder share / work-for-equity / cash-for-equity. It works exactly the same way as classic tech companies after they have gone pubilc: their equity has already been allocated but you can trade their shares on exchanges and become a shareholder. Ripple is more of a DAC than a currency. Total supply is 100B XRP.
The answer is: a lot.
Who cares.
They could go out and spend XRP on lambos and yachts. Soon they wouldn't have 20% anymore.
Anyway, it's good that they have a reserve. They can use this to entice large players to become involved.
It's all very fine imagining a perfectly equal world. I don't believe such a world exists (though I do believe in equality of opportunity).
Let's say we were
distributist absolutists. Every man, woman and child on earth was given 3 acres and a cow. Within 10 years, there'd be a very rich elite and lots of poor people with nothing. All over again.
That's human nature.
Getting hung up on the "fairness" of this 20% misses the point entirely (especially when you consider that Ripple Labs have a very strong social conscience. Also, have a look at the Chris Larsen Foundation).