Spoiler: most of those farms in China where 81% of the hashing power is, are owned by the CIA, they just hide their true hashing power in different pools and country`s, for now. The USA Government has over 51% of the hashing power.

#True

What stops this? nothing, other than making each person 1 node and give equal hash rate to each participant, which would require KYC. Does not mean your KYC has to be given to a centralized body, or cooperation, but a neutral decentralized AI and blockchain can check this for us.