There are probably many other reasons why I believe proof of stake is terrible but these are a few I can think of right now.
You can also add the flaws of POS why they are considered centralized
- Wealth centralization - this means the more coins the holder has the more power he has on the system which can lead to a concentration of wealth and power among small group of people.
- Limited Validator Set - With the limited validator this can lead to centralization
- Limited Participation - PoS typically requires a certain amount of assets to participate as a validator, which can limit the number of potential participants and lead to centralization.
- Sybil attack Vulnerability - PoS systems is vulnerable to sybil attack, where attacker can create multiple identities to gain control of a large portion of network.
- Higher Barrier to entry - new participants may have a difficulty participating because of the higher entry requirement to be a validator which leads a centralization among the existing participants.
- Governance Centralization - PoS systems are often controlled by a small group of individuals or entities, giving them a disproportionate amount of control over the network's governance and decision-making processes.
Sources:
https://medium.com/stakin/centralization-of-stake-in-pos-f7ccb8f8254
https://www.quora.com/Why-does-proof-of-stake-invite-centralization
https://www.reddit.com/r/ethereum/comments/6d1mca/proof_of_stake_leads_to_centralization_with_worse/