Proof of Stake has been around since 2012 without a single recorded successful attack against it.

Congrats to Proof of Stake for being around since 2012 without a recorded successful attack against it.

Known Proof of Stake 51% attacks:

• None

Known Proof of Work 51% attacks:

Just to name a few …

• Bitcoin SV – numerous times
• Bitcoin Gold – May 2018, Jan 2020
• Ethereum Classic – numerous times
• Expanse – Jul 2019
• Feathercoin – numerous times between 2013-2016
• Litecoin Cash – Jul 2019
• Verge – Apr 2018
• Vertcoin – Oct-Dec 2019
• Zencash – numerous times
• And many more …

Even tiny PoS security budgets have remained secure for over a decade

Proof of Stake networks have been around since 2012 with Peercoin (hybrid PoW + PoS), Blackcoin, and Nxt being the earliest. Since then, there have been numerous PoS networks including Cardano, Algorand, Ethereum, Avalanche, Cosmos, Polkadot, Tron, BSC, Fantom, Solana, IOTA.

Some of these networks (Nxt, Peercoin, IOTA) are practically dead, and yet the Proof of Stake protocols of their consensus protocols have never failed. This shows that even with tiny security budgets and small amounts of staking, Proof of Stake networks have relatively strong security.

Attacking PoS inflicts too much self-damage to the attacker

There's enough economic disincentive to attack a PoS network that no one bothers majority-attacking these networks.

The cost of attacking these networks requires buying up a huge portion of the stake, which in turn drives up the cost of the cryptocurrency and the cost of attacking astronomically. There's often not enough liquidity to even execute an attack. Attacking a PoS network hurts the attacker since they have a stake, and their stake is usually locked up for a short period of time.

Attacking PoW is comparatively cheap

PoW security is extremely expensive and has to be constantly maintained through honest mining, and it's still very inefficient at providing security. The moment the security budget runs low, it becomes very vulnerable to mining attacks.

When the security budget falls, miners leave, and the cost of gathering enough mining equipment to 51% attack a PoW network is orders of magnitude smaller than the amount of cryptocurrency being protected by the network. Goldfinger attacks and grief attacks have happened numerous times to PoW networks.

PoS implementation vulnerabilities

That's not to say that PoS is invulnerable. There are some implementations of PoS that are less secure than others.

Some networks like Cardano don't have lockup periods. Not having a lockup period is a major security concern since the attacker can stake, attack, and then immediately sell. In addition, PoS without slashing is convenient, but it's less secure than with slashing since attackers don't have to worry about misbehavior.

But even with less-secure designs, it's still much more secure than PoW. The attacker would need to magically find enough buyers on the market to sell 10-50% of the entire marketcap. And after the attacker sells, the network would go back to being secure. It's a very expensive cost to briefly censor a network. It's completely impractical when there are easier PoW targets to go after.