Why Proof of Stake (PoS), an alternative to the energy-wasting Proof of Work (PoW), is not currently able to secure blockchain cryptocurrencies.

A topic not emphasized enough with PoS protocols is their lack of resilience in dealing with worst-case scenarios. (...)

Thinking about worst case scenarios is an absolute must when dealing with critical systems, and even more important when these systems are on the global scale. (...)

So how resilient is a PoW or PoS system under these scenarios? Let’s go through some examples.
- The entire network is forced offline for some period. Then reboot.
- Some portions of the network get partitioned from the main network.
- PoS also fares worse in other worst case scenarios such as stolen private keys.

https://medium.com/@hugonguyen/proof-of-stake-the-wrong-engineering-mindset-15e641ab65a2
https://medium.com/@hugonguyen/proof-of-stake-private-keys-attacks-and-unforgeable-costliness-the-unsung-hero-5caca70b01cb