I believe that capital seeks its wisest custodian - optimal for the overall economy if opportunities for rent-seeking are minimized or mitigated.
I agree. This was in fact the logic for the "spin-off" proposal: you launch an experimental new coin with a pre-mine distributed proportional to the unspent outputs in the bitcoin blockchain at a pre-defined point in time. The wealth distribution starts as the one already known to be efficient for bitcoin.
How can rent-seeking behavior be prevented by Proof-Of-Stake?
I don't believe it can.
PoW : consensus is achieved by people who have capital at risk; rewards flow to those who perform the most work.PoS : consensus is achieved by people who have capital; rewards flow to those who have the most capital. Although "capital seeks its wisest custodian," these custodians should be rewarded for risking that capital and proving that they are wise. Not by everyone assuming they are wise because they already have the capital. To me this is the fundamental difference between PoW and PoS.
As core developer Greg Maxwell said in a thread suggesting a revival of Bitcoin P2Pool . . .
Now this is something I can support, SlipperySlope. Shifting hashpower away from the big pools and towards P2P-pool improves our consensus mechanism.
This is where we should direct our efforts IMO. I think with time, education, and the commoditization of SHA256 ASIC chips, that this will happen naturally.