agreed. Here "they'll" is not Vitalik/co, it's in control of the node validators, ofcourse you are affected by this if are in disagreement of the majority. The reason why it will be difficult to pull off a hard fork today[1].
See UASF for the success in community governance. This is good proof that the users are always in control, not miners or Vitalik.
51% is possible, but it only leads to chain reorgs, not the actual consensus rules.
In practice the actual cost and the uncertainty of an attack ensures that it is almost never attempted in practice for secure* blockchains:
1. You would need much greater hash rate share than 50% for good chances(forgoing the block rewards $$ incase of failure!), the social coordination is the bigger challenge, see mining pool distribution[1].
