The lead eth developer Vitalik has an excellent blog post addressing what it takes to fork a blockchain- https://vitalik.ca/general/2021/03/23/legitimacy.html h

The lead eth developer Vitalik has an excellent blog post addressing what it takes to fork a blockchain- https://vitalik.ca/general/2021/03/23/legitimacy.html https://vitalik.ca/general/2021/03/23/legitimacy.html The key takeaway is that yes, it's ultimately just controlled by majority agreement between users.