POS faces huge challenges in centralization. For example, the Ethereum crowd founding that was started and canceled earlier in the year, was going to keep a large chunk of Ether for the Ethereum Foundation while employing a POS algorithm. Since the Ethereum Foundation held the largest share of Ether, they necessarily would own 100% of Ether in time
This is a great point.
You might want to subscribe to the Youtube channel. I hope to produce videos on some of the major attack vectors to POS (bribing large stakeholders, nothing-at-stake minting on multiple blockchains, long-distance attacks using addresses that
used to hold coins, etc.) in future videos.
This does not seem like a great point or even a good point to me. No matter what your ownership percentage it will not increase nor decrease only because of Proof-of-Stake design.
Proof-of-Stake is inherently decentralizing by design. In contrast Proof-of-Work design is inherently centralizing.