What Is Blockchain: Computers That Can Make Commitments
a16z.comIf you control the computing you control the commitments.
The 51% attack:
https://coinmarketcap.com/alexandria/article/what-happens-in...
This has demonstrated itself to be very unlikely to happen in large blockchains such as ETH because of cryptoeconomics - ie game theory 101 - if you do a 51% attack on a blockchain you're actually devaluing the entire chain.
It's like robbing a bank where if you take enough money you cause hyperinflation.
So it appears to become less common over time as the chain gains enormous amounts of value. Proof of Stake will also lead to this sort of attack being less likely, I'd think, since it's virtually impossible for a single individual to get 51% of a well-distributed token.
It's telling that the attack here listed happened in BSV, a sort of failed fork of BTC with relatively low adoption.
Proof-of-work consensus mechanism makes sure, as the blockchain grows, transactions become MORE expensive. Discarding PoW in favour of PoS or DPoS just makes 51% attack easier. It's far easier to control 51% of coins than to control 51% of CPU power. We are not talking about single individual but a nation state or a consortium that can control the network. They may not do it for hacking it, but to control it and enrich themselves. Essentially centralizing the token which was supposed to be decentralized and remove the middleman.
The point is that it can be highly unlikely but also within the realm of all possibilities. And let's not forget the joy someone might get from wiping out the crypto bourgeoise.