Much has been written about Proof-of-Stake (PoS).
There are many ways to slice and dice PoS and uncover its weaknesses. Mainly:
Evolutionary Psychology/History: “Collectibles” or “proto-money” in history all had one thing in common, unforgeable costliness  — or at least unforgeable costliness in the context of their times. From sea shells, furs, teeth, to precious metals to minted coins. As PoS merely involves the temporary lockup of existing capital and does not consume said capital, it does not satisfy the unforgeable costliness requirement that Nick Szabo identified as one of the 3 key properties of money.