*Steel man Proof-of-Stake thesis:
“The problem of “costless simulation” aka “long range attacks” which all PoS models supposedly suffer from has long been addressed and is solved by checkpointing!”
The response by Hugo Nguyen (Founder of Nunchuk):
“Finalization” is another made-up and misleading concept in PoS. There’s no such thing as “finalized” when it comes to distributed consensus. Even in Bitcoin, everything is probabilistic.
Checkpoints are not a solution, more like kicking the can down the road. Just because you talk about a problem for years it doesn’t mean it magically goes away. We all want to be able to teleport but can we wish it into existence? There are fundamental / physical limits you can never go against. And this is also true for networking challenges.
Using checkpoints to solve difficult / nasty consensus issues is like saying “we can’t decide on chain consensus, so we’ll resort to another thing that somehow magically already has consensus”. It’s circular logic. Agreeing on a common source of randomness is another circular problem in PoS. The circularity is a recurrent and inescapable theme in PoS because you are really – I mean really – creating things out of nothing.
Stakers cannot just “move their stake elsewhere” because staking via pools requires lockin. You no longer have custody of your own money. PoS designers try to mitigate this by separating the withdrawal key from the validating key, but it’s a band-aid solution. Even with a separate offline withdrawal key, your balance can be slashed to zero in the meantime, and you absolutely have no control over this process. Miners always have full control over their hardware and point them where they want to.
I don’t know what else to tell you about “cost” being a temporary thing in PoS and there’s a missing Time element in PoS security model. It doesn’t get more basic than this. It looks “secure” at one moment in time, but it’s not when you zoom out on a long time frame or when shit hits the fan.
Plenty of examples of PoS screwing up. Solana for one was halted several times in a single calendar year. Avalanche had consensus issues. Other once popular PoS projects are dead. But this is besides the point. In reality most of these PoS projects are decentralized in name only (DINOs), so even if they make it to production bugs can easily get swept under the rug by a centralized entity. You wouldn’t know it if it fails (do you ever run a PoS full node or inspect its code base?).
Zooming out, most financial systems of the past 50 years are variants of PoS system IRL. So you can say their failures / imminent failures are also proof that it doesn’t work.
Further reading:
Can You Trust Proof-of-Stake (PoS) Security – The Checkpointing Case?
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