Many large blockchains are now dominated by only a few miners.
- 90% of Bitcoin mined by only 16 miners
- majority of Ethereum is by 3 different miners Quorum systems can offer less centralisation (e.g. 20 miners for 100% instead of 16 for 90%) at a lower resource cost.
Previously pools have gone above 51% in bitcoin, but did not disband, despite this being unacceptable behaviour.
[[51% Attack]]