Also the courts that enforce the contracts visa makes, the FBI that chases people who commit fraud, the police and jails who enforce the decisions of the court, etc etc.
A society without contracts, police, or jails is a failed society where you will not be able to reliably power your computer, and where you will be too busy fending off looters to care about blockchain anymore.
Bitcoin doesn't even try to replace contracts. Hard-line Ethereum Classic fans think they can replace contracts (they won't).
No that's that makes blockchain so fascinating. It operates well in countries with no infrastructure. Bitcoin is incredibly popular in Venezuela despite being completely illegal and actively hunted by the government, and despite the who country being very unstable.
You can't use a blockchain to protect your land rights, but you can use it to protect digital rights and that means you don't need external resources like courts to spend their time on digital rights. They can focus entirely on land conflicts and other physical matters, which will make them cheaper overall.
So living off of Bitcoin and the black market in Venezuela is your idea of what we should aspire to?
Even if a few people in Venezuela manage to use Bitcoin (propped up by the US dollar, nobody's selling their Bitcoin for Venezuelan currency), that still easily meets my definition of a failed society.
Payment systems like visa are relatively cheap to operate when being used honestly. There may be overhead when people commit fraud, but to me that seems more prudent than giving honest actors an intentionally inefficient system just to make abuse more difficult.
Since I personally don't worry about centralisation and "trust", I like the idea that a system like the blockchain could be used to revolutionise payments without the need for tin foil hats and proof-of-work.
Still, let's hope Bitcoin moves away from wasting energy soon.