So the 60 early contributors now get 12.5% of all network fees, forever? (if they "stake")?

I assume they sold some of it by now. But I see your point, does pos make the rich richer? Rich people can stake almost all their ether. since you can't move your ether for a long period of time after you stake it, staking is impractical for many. The first version of Casper will also include a minimum of ether to stake, though there are pools and they want too lower it over time.

Capital begets capital. The choice of consensus algorithm doesn't matter, as long as the system follows some kind of capitalistic economic model.

What's the incentive to participate honestly in Proof of Stake if there is no reward?

Leaving aside the question whether PoS even works at all https://download.wpsoftware.net/bitcoin/pos.pdf

You get the transaction fees. when I said block reward, I was referring to the minted coins.

On top of earning fees, if PoS includes penalties for not being honest, you will lose money by not doing the right thing.